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1.  Vitamin D supplementation in pregnancy: A systematic review 
It is unclear whether the current evidence base allows definite conclusions to be made regarding the optimal maternal circulating concentration of 25(OH)-vitamin D during pregnancy, and how this might best be achieved. CRD42011001426.
Aim/ Research Questions
What are the clinical criteria for vitamin D deficiency in pregnant women?What adverse maternal and neonatal health outcomes are associated with low maternal circulating 25(OH)-vitamin D?Does maternal supplementation with vitamin D in pregnancy lead to an improvement in these outcomes (including assessment of compliance and effectiveness)?What is the optimal type (D2 or D3), dose, regimen and route for vitamin D supplementation in pregnancy?Is supplementation with vitamin D in pregnancy likely to be cost-effective?
We performed systematic review and where possible combined study results using meta-analysis to estimate the combined effect size.
Major electronic databases were searched up to June 2012 covering both published and grey literature. Bibliographies of selected papers were hand-searched for additional references. Relevant authors were contacted for any unpublished findings and additional data if necessary.
Inclusion and exclusion criteria
Pregnant women or pregnant women and their offspring.
Either assessment of vitamin D status (dietary intake, sunlight exposure, circulating 25(OH)-vitamin D concentration) or supplementation of participants with vitamin D or vitamin D containing food e.g. oily fish.
Offspring: Birth weight, birth length, head circumference, bone mass, anthropometry and body composition, risk of asthma and atopy, small for gestational dates, preterm birth, type 1 diabetes, low birth weight, serum calcium concentration, blood pressure and rickets. Mother: Preeclampsia, gestational diabetes, risk of caesarean section and bacterial vaginosis.
76 studies were included. There was considerable heterogeneity between the studies and for most outcomes there was conflicting evidence.
The evidence base was insufficient to reliably answer question 1 in relation to biochemical or disease outcomes.
For questions 2 and 3, modest positive relationships were identified between maternal 25(OH)-vitamin D and 1) offspring birth weight in meta-analysis of 3 observational studies using log-transformed 25(OH)-vitamin D concentrations after adjustment for potential confounding factors (pooled regression coefficient 5.63g/10% change maternal 25(OH)D, 95% CI 1.11,10.16), but not in those 4 studies using natural units, or across intervention studies; 2) offspring cord blood or postnatal calcium concentrations in a meta-analysis of 6 intervention studies (all found to be at high risk of bias; mean difference 0.05mmol/l, 95% CI 0.02, 0.05); and 3) offspring bone mass in observational studies judged to be of good quality, but which did not permit meta-analysis.
The evidence base was insufficient to reliably answer questions 4 and 5.
Study methodology varied widely in terms of study design, population used, vitamin D status assessment, exposure measured and outcome definition.
The evidence base is currently insufficient to support definite clinical recommendations regarding vitamin D supplementation in pregnancy. Although there is modest evidence to support a relationship between maternal 25(OH)-vitamin D status and offspring birth weight, bone mass and serum calcium concentrations, these findings were limited by their observational nature (birth weight, bone mass) or risk of bias and low quality (calcium concentrations). High quality randomised trials are now required.
PMCID: PMC4124722  PMID: 25025896
2.  Vitamin K Supplementation in Postmenopausal Women with Osteopenia (ECKO Trial): A Randomized Controlled Trial 
PLoS Medicine  2008;5(10):1-12.
Vitamin K has been widely promoted as a supplement for decreasing bone loss in postmenopausal women, but the long-term benefits and potential harms are unknown. This study was conducted to determine whether daily high-dose vitamin K1 supplementation safely reduces bone loss, bone turnover, and fractures.
Methods and Findings
This single-center study was designed as a 2-y randomized, placebo-controlled, double-blind trial, extended for earlier participants for up to an additional 2 y because of interest in long-term safety and fractures. A total of 440 postmenopausal women with osteopenia were randomized to either 5 mg of vitamin K1 or placebo daily. Primary outcomes were changes in BMD at the lumbar spine and total hip at 2 y. Secondary outcomes included changes in BMD at other sites and other time points, bone turnover markers, height, fractures, adverse effects, and health-related quality of life. This study has a power of 90% to detect 3% differences in BMD between the two groups. The women in this study were vitamin D replete, with a mean serum 25-hydroxyvitamin D level of 77 nmol/l at baseline. Over 2 y, BMD decreased by −1.28% and −1.22% (p = 0.84) (difference of −0.06%; 95% confidence interval [CI] −0.67% to 0.54%) at the lumbar spine and −0.69% and −0.88% (p = 0.51) (difference of 0.19%; 95% CI −0.37% to 0.75%) at the total hip in the vitamin K and placebo groups, respectively. There were no significant differences in changes in BMD at any site between the two groups over the 2- to 4-y period. Daily vitamin K1 supplementation increased serum vitamin K1 levels by 10-fold, and decreased the percentage of undercarboxylated osteocalcin and total osteocalcin levels (bone formation marker). However, C-telopeptide levels (bone resorption marker) were not significantly different between the two groups. Fewer women in the vitamin K group had clinical fractures (nine versus 20, p = 0.04) and fewer had cancers (three versus 12, p = 0.02). Vitamin K supplements were well-tolerated over the 4-y period. There were no significant differences in adverse effects or health-related quality of life between the two groups. The study was not powered to examine fractures or cancers, and their numbers were small.
Daily 5 mg of vitamin K1 supplementation for 2 to 4 y does not protect against age-related decline in BMD, but may protect against fractures and cancers in postmenopausal women with osteopenia. More studies are needed to further examine the effect of vitamin K on fractures and cancers.
Trial registration: (#NCT00150969) and Current Controlled Trials (#ISRCTN61708241)
Angela Cheung and colleagues investigate whether vitamin K1 can prevent bone loss among postmenopausal women with osteopenia.
Editors' Summary
Osteoporosis is a bone disease in which the bones gradually become less dense and more likely to break. In the US, 10 million people have osteoporosis and 18 million have osteopenia, a milder condition that precedes osteoporosis. In both conditions, insufficient new bone is made and/or too much old bone is absorbed. Although bone appears solid and unchanging, very little bone in the human body is more than 10 y old. Old bone is continually absorbed and new bone built using calcium, phosphorous, and proteins. Because the sex hormones control calcium and phosphorous deposition in the bones and thus bone strength, the leading cause of osteoporosis in women is reduced estrogen levels after menopause. In men, an age-related decline in testosterone levels can cause osteoporosis. Most people discover they have osteoporosis only when they break a bone, but the condition can be diagnosed and monitored using bone mineral density (BMD) scans. Treatments can slow down or reverse bone loss (antiresorptive therapies) and some (bone formation therapies) can even make bone and build bone tissue.
Why Was This Study Done?
Although regular exercise and a healthy diet can help to keep bones strong, other ways of preventing osteoporosis are badly needed. Recently, the lay media has promoted vitamin K supplements as a way to reduce bone loss in postmenopausal women. Vitamin K (which is found mainly in leafy green vegetables) is required for a chemical modification of proteins called carboxylation. This modification is essential for the activity of three bone-building proteins. In addition, there is some evidence that low bone density and fractures are associated with a low vitamin K intake. However, little is known about the long-term benefits or harms of vitamin K supplements. In this study, the researchers investigate whether a high-dose daily vitamin K supplement can safely reduce bone loss, bone turnover, and fractures in postmenopausal women with osteopenia in a randomized controlled trial called the “Evaluation of the Clinical Use of Vitamin K Supplementation in Post-Menopausal Women With Osteopenia” (ECKO) trial.
What Did the Researchers Do and Find?
In the study, 440 postmenopausal women with osteopenia were randomized to receive 5mg of vitamin K1 (the type of vitamin K in North American food; the recommended daily adult intake of vitamin K1 is about 0.1 mg) or an inactive tablet (placebo) daily for 2 y; 261 of the women continued their treatment for 2 y to gather information about the long-term effects of vitamin K1 supplementation. All the women had regular bone density scans of their lower back and hips and were examined for fractures and for changes in bone turnover. After 2 y and after 4 y, lower back and hip bone density measurements had decreased by similar amounts in both treatment groups. The women who took vitamin K1 had 10-fold higher amounts of vitamin K1 in their blood than the women who took placebo and lower amounts of a bone formation marker; the levels of a bone resorption marker were similar in both groups. Over the 4-y period, fewer women in the vitamin K group had fractures (nine versus 20 women in the placebo group), and fewer had cancer (three versus 12). Finally, vitamin K supplementation was well tolerated over the 4-y period and adverse health effects were similar in the two treatment groups.
What Do These Findings Mean?
These findings indicate that a high daily dose of vitamin K1 provides no protection against the age-related decline in bone density in postmenopausal women with osteopenia, but that vitamin K1 supplementation may protect against fractures and cancers in these women. The apparent contradiction between the effects of vitamin K1 on bone density and on fractures could mean that vitamin K1 supplements strengthen bone by changing factors other than bone density, e.g., by changing its fine structure rather than making it denser. However, because so few study participants had fractures, the difference in the fracture rate between the two treatment groups might have occurred by chance. Larger studies are therefore needed to examine the effect of vitamin K1 on fractures (and on cancer) and, until these are done, high-dose vitamin K1 supplementation should not be recommended for the prevention of osteoporosis.
Additional Information.
Please access these Web sites via the online version of this summary at
The US National Institute of Arthritis and Musculoskeletal and Skin Diseases provides detailed information about osteoporosis (in English and Spanish) and links to other resources, including an interactive web tool called Check Up On Your Bones
MedlinePlus provides links to additional information about osteoporosis (in English and Spanish)
The MedlinePlus Encyclopedia has a page about vitamin K
The UK Food Standards Agency provides information about vitamin K
Full details about the ECKO trial are available on the Web site
The Canadian Task Force for Preventive Health Care provides recommendations on the prevention of osteoporosis and osteoporotic fractures in postmenopausal women
Osteoporosis Canada provides information on current topics related to osteoporosis
PMCID: PMC2566998  PMID: 18922041
3.  Vitamin D supplementation for women during pregnancy 
Vitamin D deficiency or insufficiency is thought to be common among pregnant women. Vitamin D supplementation during pregnancy has been suggested as an intervention to protect against adverse gestational outcomes.
To examine whether supplements with vitamin D alone or in combination with calcium or other vitamins and minerals given to women during pregnancy can safely improve maternal and neonatal outcomes.
Search methods
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2011), the International Clinical Trials Registry Platform (ICTRP) (31 October 2011), the Networked Digital Library of Theses and Dissertations (28 October 2011) and also contacted relevant organisations (8 April 2011).
Selection criteria
Randomised and quasi-randomised trials with randomisation at either individual or cluster level, evaluating the effect of supplementation with vitamin D alone or in combination with other micronutrients for women during pregnancy.
Data collection and analysis
Two review authors independently i) assessed the eligibility of studies against the inclusion criteria ii) extracted data from included studies, and iii) assessed the risk of bias of the included studies. Data were checked for accuracy.
Main results
The search strategy identified 34 potentially eligible references. We included six trials assessing a total of 1023 women, excluded eight studies, and 10 studies are still ongoing. Five trials involving 623 women compared the effects of vitamin D alone versus no supplementation/placebo and one trial with 400 women compared the effects of vitamin D and calcium versus no supplementation.
Only one trial with 400 women reported on pre-eclampsia: women who received 1200 IU vitamin D along with 375 mg of elemental calcium per day were as likely to develop pre-eclampsia as women who received no supplementation (average risk ratio (RR) 0.67; 95% confidence interval (CI) 0.33 to 1.35). Data from four trials involving 414 women consistently show that women who received vitamin D supplements had higher concentrations of vitamin D in serum at term than those women who received no intervention or a placebo; however the magnitude of the response was highly heterogenous.
Data from three trials involving 463 women suggest that women who receive vitamin D supplements during pregnancy less frequently had a baby with a birthweight below 2500 grams than those women receiving no treatment or placebo; statistical significance was borderline (RR 0.48; 95% CI 0.23 to 1.01).
In terms of other conditions, there were no significant differences in adverse side effects including nephritic syndrome (RR 0.17; 95% CI 0.01 to 4.06; one trial, 135 women); stillbirths (RR 0.17; 95% CI 0.01 to 4.06; one trial, 135 women) or neonatal deaths (RR 0.17; 95% CI 0.01 to 4.06; one trial, 135 women) between women who received vitamin D supplements in comparison with women who received no treatment or placebo. No studies reported on preterm birth, maternal death, admission to neonatal intensive care unit/special nursery or Apgar scores.
Authors' conclusions
Vitamin D supplementation in a single or continued dose during pregnancy increases serum vitamin D concentrations as measured by 25-hydroxyvitamin D at term. The clinical significance of this finding and the potential use of this intervention as a part of routine antenatal care are yet to be determined as the number of high quality trials and outcomes reported is too limited to draw conclusions on its usefulness and safety. Further rigorous randomised trials are required to evaluate the role of vitamin D supplementation in pregnancy.
PMCID: PMC3747784  PMID: 22336854
4.  Maternal antenatal vitamin D status and offspring muscle development: findings from the Southampton Women’s Survey 
The Journal of clinical endocrinology and metabolism  2013;99(1):10.1210/jc.2013-3241.
Maternal 25-hydroxy-vitamin D [25(OH)D] status in pregnancy has been associated with offspring bone development and adiposity. Vitamin D has also been implicated in postnatal muscle function but little is known about a role for antenatal 25(OH)D exposure in programming muscle development.
We investigated the associations between maternal plasma 25(OH)D status at 34 weeks gestation and offspring lean mass and muscle strength at 4 years of age.
Design and setting
A prospective UK population-based mother-offspring cohort: the Southampton Women’s Survey (SWS).
12583 non-pregnant women were initially recruited into SWS, of which 3159 had singleton pregnancies. 678 mother-child pairs were included in this analysis.
Main Outcomes Measured
At 4 years of age, offspring assessments included hand grip strength (Jamar Dynamometer) and whole body DXA (Hologic Discovery) yielding lean mass and %lean mass. Physical activity was assessed by 7-day accelerometry (Actiheart) in a subset of children (n=326).
Maternal serum 25(OH)D concentration in pregnancy was positively associated with offspring height-adjusted hand grip strength (β=0.10 SD/SD, p=0.013), which persisted after adjustment for maternal confounding factors, duration of breastfeeding and child’s physical activity at 4 years (β=0.13 SD/SD, p=0.014). Maternal 25(OH)D was also positively associated with offspring %lean mass (β=0.11 SD/SD, p=0.006), but not total lean mass (β=0.06, p=0.15). This however did not persist after adjustment for confounding factors (β=0.09 SD/SD, p=0.11).
This observational study suggests that intrauterine exposure to 25(OH)D during late pregnancy might influence offspring muscle development through an effect primarily on muscle strength rather than muscle mass.
PMCID: PMC3880861  PMID: 24178796
vitamin D; grip strength; muscle mass; fetal programming
5.  Double blind, cluster randomised trial of low dose supplementation with vitamin A or β carotene on mortality related to pregnancy in Nepal 
BMJ : British Medical Journal  1999;318(7183):570-575.
To assess the impact on mortality related to pregnancy of supplementing women of reproductive age each week with a recommended dietary allowance of vitamin A, either preformed or as β carotene.
Double blind, cluster randomised, placebo controlled field trial.
Rural southeast central plains of Nepal (Sarlahi district).
44 646 married women, of whom 20 119 became pregnant 22 189 times.
270 wards randomised to 3 groups of 90 each for women to receive weekly a single oral supplement of placebo, vitamin A (7000 μg retinol equivalents) or β carotene (42 mg, or 7000 μg retinol equivalents) for over 3½ years.
Main outcome measures
All cause mortality in women during pregnancy up to 12 weeks post partum (pregnancy related mortality) and mortality during pregnancy to 6 weeks postpartum, excluding deaths apparently related to injury (maternal mortality).
Mortality related to pregnancy in the placebo, vitamin A, and β carotene groups was 704, 426, and 361 deaths per 100 000 pregnancies, yielding relative risks (95% confidence intervals) of 0.60 (0.37 to 0.97) and 0.51 (0.30 to 0.86). This represented reductions of 40% (P<0.04) and 49% (P<0.01) among those who received vitamin A and β carotene. Combined, vitamin A or β carotene lowered mortality by 44% (0.56 (0.37 to 0.84), P<0.005) and reduced the maternal mortality ratio from 645 to 385 deaths per 100 000 live births, or by 40% (P<0.02). Differences in cause of death could not be reliably distinguished between supplemented and placebo groups.
Supplementation of women with either vitamin A or β carotene at recommended dietary amounts during childbearing years can lower mortality related to pregnancy in rural, undernourished populations of south Asia.
Key messagesMaternal vitamin A deficiency, evident as night blindness or low serum retinol concentration during pregnancy, is widely prevalent in rural south AsiaIn Nepal, women of reproductive age who were given 7000 μg retinol equivalents of vitamin A on a weekly basis showed a reduction in mortality related to pregnancy of 40%Weekly dosing with 42 mg β carotene (also providing 7000 μg retinol equivalents) lowered their mortality by 49%Preventing maternal vitamin A deficiency in rural South Asia can lower the risk of mortality of women during and after pregnancy
PMCID: PMC27760  PMID: 10037634
6.  Childhood bone mineral content is associated with methylation status of the RXRA promoter at birth 
Maternal vitamin D deficiency has been associated with reduced offspring bone mineral accrual. Retinoid-X Receptor-alpha (RXRA) is an essential cofactor in the action of 1,25(OH)2-vitamin D, and RXRA methylation in umbilical cord DNA has been associated with later offspring adiposity. We tested the hypothesis that RXRA methylation in umbilical cord DNA collected at birth is associated with offspring skeletal development, assessed by dual-energy X-ray absorptiometry, in a population-based mother-offspring cohort (Southampton Women’s Survey). Relationships between maternal plasma 25(OH)-vitamin D concentrations and cord RXRA methylation were also investigated. In 230 children aged 4 years, higher % methylation at 4 out of 6 RXRA CpG sites measured was correlated with lower offspring % bone mineral content (%BMC) (β=−0.02 to −0.04%/SD, p=0.002 to 0.043) and BMC corrected for body size (β=−2.1 to −3.4g/SD, p=0.002 to 0.047), with a further site associated with %BMC only. Similar relationships for %BMC were observed in a second independent cohort (n=64). Maternal free 25(OH)-vitamin D index was negatively associated with methylation at one of these RXRA CpG sites (β=−3.3 SD/unit, p=0.03). In addition to the mechanistic insights afforded by associations between maternal free 25(OH)-vitamin D index, RXRA methylation in umbilical cord DNA, and childhood BMC, such epigenetic marks in early life might represent novel biomarkers for adverse bone outcomes in the offspring.
PMCID: PMC3836689  PMID: 23907847
Epigenetic; methylation; umbilical cord; RXRA; vitamin D; DXA
7.  Preconceptional Folate Supplementation and the Risk of Spontaneous Preterm Birth: A Cohort Study 
PLoS Medicine  2009;6(5):e1000061.
In an analysis of a cohort of pregnant women, Radek Bukowski and colleagues describe an association between taking folic acid supplements and a reduction in the risk of preterm birth.
Low plasma folate concentrations in pregnancy are associated with preterm birth. Here we show an association between preconceptional folate supplementation and the risk of spontaneous preterm birth.
Methods and Findings
In a cohort of 34,480 low-risk singleton pregnancies enrolled in a study of aneuploidy risk, preconceptional folate supplementation was prospectively recorded in the first trimester of pregnancy. Duration of pregnancy was estimated based on first trimester ultrasound examination. Natural length of pregnancy was defined as gestational age at delivery in pregnancies with no medical or obstetrical complications that may have constituted an indication for delivery. Spontaneous preterm birth was defined as duration of pregnancy between 20 and 37 wk without those complications. The association between preconceptional folate supplementation and the risk of spontaneous preterm birth was evaluated using survival analysis. Comparing to no supplementation, preconceptional folate supplementation for 1 y or longer was associated with a 70% decrease in the risk of spontaneous preterm delivery between 20 and 28 wk (41 [0.27%] versus 4 [0.04%] spontaneous preterm births, respectively; HR 0.22, 95% confidence interval [CI] 0.08–0.61, p = 0.004) and a 50% decrease in the risk of spontaneous preterm delivery between 28 and 32 wk (58 [0.38%] versus 12 [0.18%] preterm birth, respectively; HR 0.45, 95% CI 0.24–0.83, p = 0.010). Adjustment for maternal characteristics age, race, body mass index, education, marital status, smoking, parity, and history of prior preterm birth did not have a material effect on the association between folate supplementation for 1 y or longer and spontaneous preterm birth between 20 and 28, and 28 to 32 wk (adjusted HR 0.31, 95% CI 0.11–0.90, p = 0.031 and 0.53, 0.28–0.99, p = 0.046, respectively). Preconceptional folate supplementation was not significantly associated with the risk of spontaneous preterm birth beyond 32 wk. The association between shorter duration (<1 y) of preconceptional folate supplementation and the risk of spontaneous preterm birth was not significant after adjustment for maternal characteristics. However, the risk of spontaneous preterm birth decreased with the duration of preconceptional folate supplementation (test for trend of survivor functions, p = 0.01) and was the lowest in women who used folate supplementation for 1 y or longer. There was also no significant association with other complications of pregnancy studied after adjustment for maternal characteristics.
Preconceptional folate supplementation is associated with a 50%–70% reduction in the incidence of early spontaneous preterm birth. The risk of early spontaneous preterm birth is inversely proportional to the duration of preconceptional folate supplementation. Preconceptional folate supplementation was specifically related to early spontaneous preterm birth and not associated with other complications of pregnancy.
Editors' Summary
Most pregnancies last about 40 weeks, but sometimes the new family member arrives early. Every year, half a million babies in the United States (12.5% of all babies) are born prematurely (before 37 completed weeks of pregnancy). Sadly, premature babies are more likely to die than full-term babies and many have short- and/or long-term health problems. Premature babies often have breathing problems, they are susceptible to life-threatening infections, and they are more likely to have learning and developmental disabilities than those born on time. The severity of these health problems depends on the degree of prematurity—preterm babies born between 34 and 36 weeks of pregnancy rarely develop severe disabilities, but a quarter of babies born before 28 weeks of pregnancy develop serious lasting disabilities and half have learning and behavioral problems. Although doctors have identified some risk factors for early delivery (for example, smoking), it is impossible to predict who will have an early birth and there is no effective way to prevent preterm births.
Why Was This Study Done?
Some researchers think that folate supplements may prevent preterm births. Folate (folic acid), a vitamin found in leafy green vegetables, fruits, and dried beans, helps to prevent neural tube birth defects. Consequently, women are encouraged to take folic acid supplements throughout (and preferably before) pregnancy and many governments now mandate that bread, pasta, and other grain products be fortified with folic acid to help women get sufficient folate. There is some evidence that women who deliver early have less folate in their blood than women who deliver at term. Furthermore, folate supplementation during pregnancy has increased the length of pregnancy in some but not all clinical trials. A possible explanation for these mixed results is that the duration of pregnancy reflects conditions in the earliest stages of pregnancy or before conception and that folate supplementation needs to start before conception to reduce the risk of preterm birth. In this study, the researchers test this idea by analyzing data collected from nearly 35,000 pregnant women enrolled in a study that was originally designed to investigate screening for Down's syndrome.
What Did the Researchers Do and Find?
During the first three months of their pregnancy, the women were asked whether they had taken folate supplements before conception. The duration of each pregnancy was estimated from ultrasound measurements taken early in the pregnancy and from the time of delivery. During the study, 1,658 women had spontaneous preterm deliveries before 37 weeks and 160 delivered before 32 weeks. After allowing for other maternal characteristics that might have affected the likelihood of preterm delivery, the risk of spontaneous preterm delivery between 20 and 28 weeks was 70% lower in women who took folate supplements for more than a year before becoming pregnant than in women who didn't take a supplement. Long-term folate supplementation also reduced the risk of preterm delivery between 28 and 32 weeks by 50% but did not affect the risk of preterm birth beyond 32 weeks. Folate supplementation for less than a year before conception did not reduce the risk of preterm birth, and folate supplementation was not associated with any other complications of pregnancy.
What Do These Findings Mean?
These findings show that folate supplementation for a year or more before conception is associated with a 50%–70% decrease in early (but not late) spontaneous preterm births and that the longer a woman takes folate supplements before becoming pregnant, the lower her risk of a preterm birth. Although the researchers allowed for maternal characteristics that might have affected the duration of pregnancy, it is possible that folate supplementation may not be responsible for the reduction in preterm birth risk seen in this study. For example, taking folate supplements may be a marker of healthy behavior and the women taking the supplements might have been doing something else that was reducing their risk of preterm birth. However, despite this and other limitations of this study, these findings suggest that long-term folate supplementation before conception is worth investigating further as a potential way to prevent preterm births.
Additional Information
Please access these Web sites via the online version of this summary at
This study is further discussed in a PLoS Medicine Perspective by Nicholas Fisk
The MedlinePlus encyclopedia contains a page on premature babies (in English and Spanish); MedlinePlus provides links to other information on premature babies (in English and Spanish)
The US National Institute of Child Health and Human Development provides information on preterm labor and birth
The March of Dimes, a nonprofit organization for pregnancy and baby health, provides information on preterm birth and on folic acid (in English and Spanish)
The Nemours Foundation, another nonprofit organization for child health, also provides information on premature babies (in English and Spanish)
The US Office of Dietary Supplements has a fact sheet on folate
PMCID: PMC2671168  PMID: 19434228
8.  Effects and safety of periconceptional folate supplementation for preventing birth defects 
It has been reported that neural tube defects can be prevented with periconceptional folic acid supplementation. The effects of different doses, forms and schemes of folate supplementation for the prevention of other birth defects and maternal and infant outcomes are unclear.
This review updates and expands a previous Cochrane Review assessing the effects of periconceptional supplementation with folic acid to reduce neural tube defects (NTDs). We examined whether folate supplementation before and during early pregnancy can reduce neural tube and other birth defects (including cleft palate) without causing adverse outcomes for mothers or babies.
Search methods
We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register (July 2010). Additionally, we searched the international clinical trials registry platform and contacted relevant organisations to identify ongoing and unpublished studies.
Selection criteria
We included all randomised or quasi-randomised trials evaluating the effect of periconceptional folate supplementation alone, or in combination with other vitamins and minerals, in women independent of age and parity.
Data collection and analysis
We assessed trials for methodological quality using the standard Cochrane criteria. Two authors independently assessed the trials for inclusion, one author extracted data and a second checked for accuracy.
Main results
Five trials involving 6105 women (1949 with a history of a pregnancy affected by a NTD and 4156 with no history of NTDs) were included. Overall, the results are consistent in showing a protective effect of daily folic acid supplementation (alone or in combination with other vitamins and minerals) in preventing NTDs compared with no interventions/placebo or vitamins and minerals without folic acid (risk ratio (RR) 0.28, 95% confidence interval (CI) 0.15 to 0.52). Only one study assessed the incidence of NTDs and the effect was not statistically significant (RR 0.08, 95% CI 0.00 to 1.33) although no events were found in the group that received folic acid. Folic acid had a significant protective effect for reoccurrence (RR 0.32, 95% CI 0.17 to 0.60). There is no statistically significant evidence of any effects on prevention of cleft palate, cleft lip, congenital cardiovascular defects, miscarriages or any other birth defects. There were no included trials assessing the effects of this intervention on maternal blood folate or anaemia at term.
We found no evidence of short-term side effects.
Authors’ conclusions
Folic acid, alone or in combination with vitamins and minerals, prevents NTDs but does not have a clear effect on other birth defects.
PMCID: PMC4160020  PMID: 20927767
Dietary Supplements; Folic Acid [* administration & dosage]; Neural Tube Defects [* prevention & control]; Randomized Controlled Trials as Topic; Vitamin B Complex [* administration & dosage]; Female; Humans; Infant; Pregnancy
9.  Cord Blood 25(OH)-Vitamin D Deficiency and Childhood Asthma, Allergy and Eczema: The COPSAC2000 Birth Cohort Study 
PLoS ONE  2014;9(6):e99856.
Epidemiological studies have suggested an association between maternal vitamin D dietary intake during pregnancy and risk of asthma and allergy in the offspring. However, prospective clinical studies on vitamin D measured in cord blood and development of clinical end-points are sparse.
To investigate the interdependence of cord blood 25-hydroxyvitamin D (25(OH)-Vitamin D) level and investigator-diagnosed asthma- and allergy-related conditions during preschool-age.
Cord blood 25(OH)-Vitamin D level was measured in 257 children from the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC2000) at-risk mother-child cohort. Troublesome lung symptoms (TROLS), asthma, respiratory infections, allergic rhinitis, and eczema, at age 0–7 yrs were diagnosed exclusively by the COPSAC pediatricians strictly adhering to predefined algorithms. Objective assessments of lung function and sensitization were performed repeatedly from birth.
After adjusting for season of birth, deficient cord blood 25(OH)-Vitamin D level (<50 nmol/L) was associated with a 2.7-fold increased risk of recurrent TROLS (HR = 2.65; 95% CI = 1.02–6.86), but showed no association with respiratory infections or asthma. We saw no association between cord blood 25(OH)-Vitamin D level and lung function, sensitization, rhinitis or eczema. The effects were unaffected from adjusting for multiple lifestyle factors.
Cord blood 25(OH)-Vitamin D deficiency associated with increased risk of recurrent TROLS till age 7 years. Randomized controlled trials of vitamin D supplementation during pregnancy are needed to prove causality.
PMCID: PMC4055727  PMID: 24925304
10.  Intermittent oral iron supplementation during pregnancy (Review) 
Anaemia is a frequent condition during pregnancy, particularly among women from developing countries who have insufficient iron intake to meet increased iron needs of both the mother and the fetus. Traditionally, gestational anaemia has been prevented with the provision of daily iron supplements throughout pregnancy, but adherence to this regimen due to side effects, interrupted supply of the supplements, and concerns about safety among women with an adequate iron intake, have limited the use of this intervention. Intermittent (i.e. one, two or three times a week on non-consecutive days) supplementation with iron alone or in combination with folic acid or other vitamins and minerals has recently been proposed as an alternative to daily supplementation.
To assess the benefits and harms of intermittent supplementation with iron alone or in combination with folic acid or other vitamins and minerals to pregnant women on neonatal and pregnancy outcomes.
Search methods
We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register (23 March 2012). We also searched the WHO International Clinical Trials Registry Platform (ICTRP) for ongoing studies and contacted relevant organisations for the identification of ongoing and unpublished studies (23 March 2012).
Selection criteria
Randomised or quasi-randomised trials.
Data collection and analysis
We assessed the methodological quality of trials using standard Cochrane criteria. Two review authors independently assessed trial eligibility, extracted data and conducted checks for accuracy.
Main results
This review includes 21 trials from 13 different countries, but only 18 trials (with 4072 women) reported on our outcomes of interest and contributed data to the review. All of these studies compared daily versus intermittent iron supplementation.
Three studies provided iron alone, 12 iron+folic acid and three more iron plus multiple vitamins and minerals. Their methodological quality was mixed and most had high levels of attrition. Overall, there was no clear evidence of differences between groups for infant primary outcomes: low birthweight (average risk ratio (RR) 0.96; 95% confidence interval (CI) 0.61 to 1.52, seven studies), infant birthweight (mean difference MD −8.62 g; 95% CI −52.76 g to 35.52 g, eight studies), premature birth (average RR 1.82; 95% CI 0.75 to 4.40, four studies). None of the studies reported neonatal deaths or congenital anomalies.
For maternal outcomes, there was no clear evidence of differences between groups for anaemia at term (average RR 1.22; 95% CI 0.84 to 1.80, four studies) and women receiving intermittent supplementation had less side effects (average RR 0.56; 95% CI 0.37 to 0.84, 11 studies) than those receiving daily supplements. Women receiving intermittent supplements were also at lower risk of having high haemoglobin (Hb) concentrations (greater than 130 g/L) during the second or third trimester of pregnancy (average RR 0.48; 95% CI 0.35 to 0.67, 13 studies). There were no significant differences in iron-deficiency anaemia between women receiving intermittent or daily iron+folic acid supplementation (average RR 0.71; 95% CI 0.08 to 6.63, 1 study). There were no maternal deaths (six studies) or women with severe anaemia in pregnancy (six studies). None of the studies reported on iron deficiency at term or infections during pregnancy.
Where sufficient data were available for primary outcomes, we set up subgroups to look for possible differences between studies in terms of earlier or later supplementation; women’s anaemia status at the start of supplementation; higher and lower weekly doses of iron; and the malarial status of the region in which the trials were conducted. There was no clear effect of these variables on the results of the review.
Authors’ conclusions
The present systematic review is the most comprehensive summary of the evidence assessing the benefits and harms of intermittent iron supplementation regimens in pregnant women on haematological and pregnancy outcomes. The findings suggest that intermittent iron+folic acid regimens produce similar maternal and infant outcomes at birth as daily supplementation but are associated with fewer side effects. Women receiving daily supplements had increased risk of developing high levels of Hb in mid and late pregnancy but were less likely to present mild anaemia near term. Although the evidence is limited and the quality of the trials was low or very low, intermittent may be a feasible alternative to daily iron supplementation among those pregnant women who are not anaemic and have adequate antenatal care.
PMCID: PMC4053594  PMID: 22786531
*Dietary Supplements [adverse effects]; Administration, Oral; Anemia, Iron-Deficiency [blood; *prevention & control]; Developing Countries; Drug Administration Schedule; Drug Combinations; Folic Acid [administration & dosage]; Hemoglobin A [metabolism]; Infant, Low Birth Weight; Infant, Newborn; Iron [*administration & dosage; adverse effects]; Iron, Dietary [*administration & dosage]; Pregnancy Complications, Hematologic [blood; prevention & control]; Premature Birth; Randomized Controlled Trials as Topic; Vitamins [administration & dosage]; Female; Humans; Pregnancy
11.  Prenatal Vitamin D Supplementation and Child Respiratory Health: A Randomised Controlled Trial 
PLoS ONE  2013;8(6):e66627.
Observational studies suggest high prenatal vitamin D intake may be associated with reduced childhood wheezing. We examined the effect of prenatal vitamin D on childhood wheezing in an interventional study.
We randomised 180 pregnant women at 27 weeks gestation to either no vitamin D, 800 IU ergocalciferol daily until delivery or single oral bolus of 200,000 IU cholecalciferol, in an ethnically stratified, randomised controlled trial. Supplementation improved but did not optimise vitamin D status. Researchers blind to allocation assessed offspring at 3 years. Primary outcome was any history of wheeze assessed by validated questionnaire. Secondary outcomes included atopy, respiratory infection, impulse oscillometry and exhaled nitric oxide. Primary analyses used logistic and linear regression.
We evaluated 158 of 180 (88%) offspring at age 3 years for the primary outcome. Atopy was assessed by skin test for 95 children (53%), serum IgE for 86 (48%), exhaled nitric oxide for 62 (34%) and impulse oscillometry of acceptable quality for 51 (28%). We found no difference between supplemented and control groups in risk of wheeze [no vitamin D: 14/50 (28%); any vitamin D: 26/108 (24%) (risk ratio 0.86; 95% confidence interval 0.49, 1.50; P = 0.69)]. There was no significant difference in atopy, eczema risk, lung function or exhaled nitric oxide between supplemented groups and controls.
Prenatal vitamin D supplementation in late pregnancy that had a modest effect on cord blood vitamin D level, was not associated with decreased wheezing in offspring at age three years.
Trial Registration ISRCTN68645785
PMCID: PMC3691177  PMID: 23826104
12.  Efficacy of Clodronate in Local and Systemic Osteoporosis 
Clodronate belongs to the first generation of the large biphosphonate family of drugs (the non-nitrogen ones), and from the earliest studies, conducted in the ’70s, it distinguished itself from etidronate, a powerful antiresorptive drug that acts at osteoclastic level but, however, causes an osteomalacic bone mineralisation deficit clearly evident on histomorphometry. Common experience and several clinical and biological studies have shown that clodronate exerts an antalgic effect not only in fracture patients but also in those affected by osteoarthrosis or athritis. The drug, therefore, can usefully be included in the treatment regimen of rheumatic patients, also on account of its symptomatic effects. Clodronate in small doses (2 mg) also appears to exert protective effects on cartilage (an intra-articular formulation is indeed to be introduced), while at doses 10–100 times higher it undoubtedly has anti-inflammatory effects and, more specifically, antimacrophage and anticytokine effects (IL-1, IL-6, TNF-alpha, PGE). These effects are amplified by the incorporation of clodronate into monolayer liposomes. The drug may therefore be considered a coadjuvant in the treatment of arthritis originating from strong osteoclast activation induced by increased levels of cytokines and by an increased RANKL/OPG ratio. It is clear that clodronate can act both upstream, on cytokines, and downstream, on the osteoclast effector function.
At local level, the anti-inflammatory and antimacrophage effect is likely at the basis of the capacity of the drug to stablilise a prosthesis, as observed at knee and at hip level.
Its impact on algodystrophic pathology, with clear reduction of bone marrow oedema as from the third month of parenteral treatment, is well known. This may also be true, albeit in the absence of adequate literature, of treatment of osteonecrosis in the first two stages, especially if it is parcellar, as seen at subchondral level in osteoarthrosis.
At systemic level, there are essentially three published studies demonstrating the anti-fracture effect of the drug: two by McCloskey, published in 2004 and 2007 in J Bone Miner Res, and our study on the prevention of fractures in corticosteroid-induced osteoporosis.
They are all controlled studies, the first two double-blind, and ours an open, controlled study.
McCloskey’s studies used 800 mg of clodronate/day per os for three years, whereas we used 100 mg of clodronate /week i.m. for four weeks.
In McCloskey’s 2004 study, 593 patients (women and men with osteoporosis or vertebral fracture), were randomised to 500 mg calcium without vitamin D or to calcium plus clodronate. Vertebral fractures were the primary endpoint.
As regards the antifracture effect, there emerged a 46% reduction in vertebral fractures in the clodronate versus the control group. The reduction was 40% in patients with post-menopausal osteoporosis and a remarkable 65% in patients with secondary osteoporosis. There was also a 73% reduction in the incidence of vertebral fractures in subjects who did not previously have fractures and a reduction of 41% in those who already had fractures. This study recorded a 30% reduction in non-vertebral fractures, which was not statistically significant. In the 2007 study, McCloskey investigated 5600 women over the age of 75 years who, on invitation to take part in the study, had consented. The patients were randomised in a double-blind manner to receive either clodronate 800 mg/day or inert placebo. Clinical and densitometric monitoring lasted three years. The primary endpoint was reduction of fractures of all types.
The sample presented some interesting features, given that no densitometric criteria had been applied in the enrolment stage: only 1 woman in 5 was osteoporotic; furthermore, subjects with other problems were excluded, and this was reflected in the fact that mortality at the end of the three years was half the expected level, and fracture episodes, too, were 50% lower than the expected level. This clearly had repercussions on the statistical power of this study.
The important finding emerging from this study is that the overall antifracture effect is present both in osteoporotic subjects (−29.5%), and in normal and osteopenic subjects (−22.5%).
As regards corticosteroid-induced osteoporosis there exist several studies that investigate bone mass, but our 2003 study published in Bone is the only one to take vertebral fractures as an endpoint and also absolutely the only one to test, using this endpoint, the 100 mg i.m. formulation.
It was a study on prevention of corticosteroid-induced osteoporosis. Indeed, the subjects (160 patients with arthritis) had started cortiscosteroid therapy within the previous 100 days. They were randomised to receive clodronate + calcium and vitamin D or only calcium and vitamin D. Each year, DXA scans, US measurement of the heel and DXA morphometry were carried out. The results showed maintenance of bone mass in the patients receiving clodronate (which was the objective, given that these were osteopenic or normal patients) while mineral loss was marked in the controls. The US heel measurements were in line with the DXA data.
An around 40% reduction in fractures overall was recorded, while multiple fractures were reduced by 75%.
Finally, in recent years the cost/benefit question has started to be raised, especially after the birth of algorithms like FRAX, which allow the selection of patients at increased ten-year fracture risk, and of pharmaco-economic models that make it possible to calculate FRAX-based intervention thresholds on the basis of drug and monitoring costs, antifracture efficacy, quality of life, and the amount that a community can or wishes to spend. In this regard, a subanalysis of patients from the McCloskey study (3974 patients aged over 65), showed that clodronate is more effective in patients with a higher FRAX-calculated fracture risk. Furthermore, another study, by Kanis, has shown that for a drug costing 100 pounds/year (very similar to the cost of clodronate), the “cost-effective” threshold for intervention is around 7–10%.
PMCID: PMC3213787
13.  Daily oral iron supplementation during pregnancy 
Iron and folic acid supplementation has been the preferred intervention to improve iron stores and prevent anaemia among pregnant women, and it may also improve other maternal and birth outcomes.
To assess the effects of daily oral iron supplements for pregnant women, either alone or in conjunction with folic acid, or with other vitamins and minerals as a public health intervention.
Search methods
We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register (2 July 2012). We also searched the WHO International Clinical Trials Registry Platform (ICTRP) (2 July 2012) and contacted relevant organisations for the identification of ongoing and unpublished studies.
Selection criteria
Randomised or quasi-randomised trials evaluating the effects of oral preventive supplementation with daily iron, iron + folic acid or iron + other vitamins and minerals during pregnancy.
Data collection and analysis
We assessed the methodological quality of trials using standard Cochrane criteria. Two review authors independently assessed trial eligibility, extracted data and conducted checks for accuracy.
Main results
We included 60 trials. Forty-three trials, involving more than 27,402 women, contributed data and compared the effects of daily oral supplements containing iron versus no iron or placebo.
Overall, women taking iron supplements were less likely to have low birthweight newborns (below 2500 g) compared with controls (8.4% versus 10.2%, average risk ratio (RR) 0.81; 95% confidence interval (CI) 0.68 to 0.97, 11 trials, 8480 women) and mean birthweight was 30.81 g greater for those infants whose mothers received iron during pregnancy (average mean difference (MD) 30.81; 95% CI 5.94 to 55.68, 14 trials, 9385 women). Preventive iron supplementation reduced the risk of maternal anaemia at term by 70% (RR 0.30; 95% CI 0.19 to 0.46, 14 trials, 2199 women) and iron deficiency at term by 57% (RR 0.43; 95% CI 0.27 to 0.66, seven trials, 1256 women). Although the difference between groups did not reach statistical significance, women who received iron supplements were more likely than controls to report side effects (25.3% versus 9.91%) (RR 2.36; 95% CI 0.96 to 5.82, 11 trials, 4418 women), particularly at doses 60 mg of elemental iron or higher. Women receiving iron were on average more likely to have higher haemoglobin (Hb) concentrations at term and in the postpartum period, but were at increased risk of Hb concentrations greater than 130g/L during pregnancy and at term. Twenty-three studies were conducted in countries that in 2011 had some malaria risk in parts of the country. In some of these countries/territories, malaria is present only in certain areas or up to a particular altitude. Only two of these reported malaria outcomes. There is no evidence that iron supplementation increases placental malaria. For some outcomes heterogeneity was higher than 50%.
Authors’ conclusions
Prenatal supplementation with daily iron are effective to reduce the risk of low birthweight, and to prevent maternal anaemia and iron deficiency in pregnancy. Associated maternal side effects and particularly high Hb concentrations during pregnancy at currently used doses suggest the need to update recommendations on doses and regimens for routine iron supplementation.
PMCID: PMC4233117  PMID: 23235616
*Dietary Supplements [adverse effects]; Anemia, Iron-Deficiency [*prevention & control]; Folic Acid [*administration & dosage]; Infant, Low Birth Weight; Infant, Newborn; Iron [*administration & dosage]; Iron, Dietary [administration & dosage]; Pregnancy Complications, Hematologic [*prevention & control]; Pregnancy Outcome; Prenatal Care [methods]; Randomized Controlled Trials as Topic; Female; Humans; Pregnancy
14.  Associations of Maternal Iron Intake and Hemoglobin in Pregnancy with Offspring Vascular Phenotypes and Adiposity at Age 10: Findings from the Avon Longitudinal Study of Parents and Children 
PLoS ONE  2014;9(1):e84684.
Iron deficiency is common during pregnancy. Experimental animal studies suggest that it increases cardiovascular risk in the offspring.
To examine the relationship between maternal pregnancy dietary and supplement iron intake and hemoglobin, with offspring’s arterial stiffness (measured by carotid-radial pulse wave velocity), endothelial function (measured by brachial artery flow mediated dilatation), blood pressure, and adiposity (measured by body mass index), test for mediation by cord ferritin, birth weight, gestational age, and child dietary iron intake, and for effect modification by maternal vitamin C intake and offspring sex.
Prospective data from 2958 mothers and children pairs at 10 years of age enrolled in an English birth cohort, the Avon Longitudinal Study for Parents and Children (ALSPAC), was analysed.
2639 (89.2%) mothers reported dietary iron intake in pregnancy below the UK reference nutrient intake of 14.8 mg/day. 1328 (44.9%) reported taking iron supplements, and 129 (4.4%) were anemic by 18 weeks gestation. No associations were observed apart from maternal iron intake from supplements with offspring systolic blood pressure (−0.8 mmHg, 99% CI −1.7 to 0, P = 0.01 in the sample with all relevant data observed, and −0.7 mmHg, 99% CI −1.3 to 0, P = 0.008 in the sample with missing data imputed).
There was no evidence of association between maternal pregnancy dietary iron intake, or maternal hemoglobin concentration (which is less likely to be biased by subjective reporting) with offspring outcomes. There was a modest inverse association between maternal iron supplement intake during pregnancy with offspring systolic blood pressure at 10 years.
PMCID: PMC3882256  PMID: 24400110
15.  Clinical Utility of Vitamin D Testing 
Executive Summary
This report from the Medical Advisory Secretariat (MAS) was intended to evaluate the clinical utility of vitamin D testing in average risk Canadians and in those with kidney disease. As a separate analysis, this report also includes a systematic literature review of the prevalence of vitamin D deficiency in these two subgroups.
This evaluation did not set out to determine the serum vitamin D thresholds that might apply to non-bone health outcomes. For bone health outcomes, no high or moderate quality evidence could be found to support a target serum level above 50 nmol/L. Similarly, no high or moderate quality evidence could be found to support vitamin D’s effects in non-bone health outcomes, other than falls.
Vitamin D
Vitamin D is a lipid soluble vitamin that acts as a hormone. It stimulates intestinal calcium absorption and is important in maintaining adequate phosphate levels for bone mineralization, bone growth, and remodelling. It’s also believed to be involved in the regulation of cell growth proliferation and apoptosis (programmed cell death), as well as modulation of the immune system and other functions. Alone or in combination with calcium, Vitamin D has also been shown to reduce the risk of fractures in elderly men (≥ 65 years), postmenopausal women, and the risk of falls in community-dwelling seniors. However, in a comprehensive systematic review, inconsistent results were found concerning the effects of vitamin D in conditions such as cancer, all-cause mortality, and cardiovascular disease. In fact, no high or moderate quality evidence could be found concerning the effects of vitamin D in such non-bone health outcomes. Given the uncertainties surrounding the effects of vitamin D in non-bone health related outcomes, it was decided that this evaluation should focus on falls and the effects of vitamin D in bone health and exclusively within average-risk individuals and patients with kidney disease.
Synthesis of vitamin D occurs naturally in the skin through exposure to ultraviolet B (UVB) radiation from sunlight, but it can also be obtained from dietary sources including fortified foods, and supplements. Foods rich in vitamin D include fatty fish, egg yolks, fish liver oil, and some types of mushrooms. Since it is usually difficult to obtain sufficient vitamin D from non-fortified foods, either due to low content or infrequent use, most vitamin D is obtained from fortified foods, exposure to sunlight, and supplements.
Clinical Need: Condition and Target Population
Vitamin D deficiency may lead to rickets in infants and osteomalacia in adults. Factors believed to be associated with vitamin D deficiency include:
darker skin pigmentation,
winter season,
living at higher latitudes,
skin coverage,
kidney disease,
malabsorption syndromes such as Crohn’s disease, cystic fibrosis, and
genetic factors.
Patients with chronic kidney disease (CKD) are at a higher risk of vitamin D deficiency due to either renal losses or decreased synthesis of 1,25-dihydroxyvitamin D.
Health Canada currently recommends that, until the daily recommended intakes (DRI) for vitamin D are updated, Canada’s Food Guide (Eating Well with Canada’s Food Guide) should be followed with respect to vitamin D intake. Issued in 2007, the Guide recommends that Canadians consume two cups (500 ml) of fortified milk or fortified soy beverages daily in order to obtain a daily intake of 200 IU. In addition, men and women over the age of 50 should take 400 IU of vitamin D supplements daily. Additional recommendations were made for breastfed infants.
A Canadian survey evaluated the median vitamin D intake derived from diet alone (excluding supplements) among 35,000 Canadians, 10,900 of which were from Ontario. Among Ontarian males ages 9 and up, the median daily dietary vitamin D intake ranged between 196 IU and 272 IU per day. Among females, it varied from 152 IU to 196 IU per day. In boys and girls ages 1 to 3, the median daily dietary vitamin D intake was 248 IU, while among those 4 to 8 years it was 224 IU.
Vitamin D Testing
Two laboratory tests for vitamin D are available, 25-hydroxy vitamin D, referred to as 25(OH)D, and 1,25-dihydroxyvitamin D. Vitamin D status is assessed by measuring the serum 25(OH)D levels, which can be assayed using radioimmunoassays, competitive protein-binding assays (CPBA), high pressure liquid chromatography (HPLC), and liquid chromatography-tandem mass spectrometry (LC-MS/MS). These may yield different results with inter-assay variation reaching up to 25% (at lower serum levels) and intra-assay variation reaching 10%.
The optimal serum concentration of vitamin D has not been established and it may change across different stages of life. Similarly, there is currently no consensus on target serum vitamin D levels. There does, however, appear to be a consensus on the definition of vitamin D deficiency at 25(OH)D < 25 nmol/l, which is based on the risk of diseases such as rickets and osteomalacia. Higher target serum levels have also been proposed based on subclinical endpoints such as parathyroid hormone (PTH). Therefore, in this report, two conservative target serum levels have been adopted, 25 nmol/L (based on the risk of rickets and osteomalacia), and 40 to 50 nmol/L (based on vitamin D’s interaction with PTH).
Ontario Context
Volume & Cost
The volume of vitamin D tests done in Ontario has been increasing over the past 5 years with a steep increase of 169,000 tests in 2007 to more than 393,400 tests in 2008. The number of tests continues to rise with the projected number of tests for 2009 exceeding 731,000. According to the Ontario Schedule of Benefits, the billing cost of each test is $51.7 for 25(OH)D (L606, 100 LMS units, $0.517/unit) and $77.6 for 1,25-dihydroxyvitamin D (L605, 150 LMS units, $0.517/unit). Province wide, the total annual cost of vitamin D testing has increased from approximately $1.7M in 2004 to over $21.0M in 2008. The projected annual cost for 2009 is approximately $38.8M.
Evidence-Based Analysis
The objective of this report is to evaluate the clinical utility of vitamin D testing in the average risk population and in those with kidney disease. As a separate analysis, the report also sought to evaluate the prevalence of vitamin D deficiency in Canada. The specific research questions addressed were thus:
What is the clinical utility of vitamin D testing in the average risk population and in subjects with kidney disease?
What is the prevalence of vitamin D deficiency in the average risk population in Canada?
What is the prevalence of vitamin D deficiency in patients with kidney disease in Canada?
Clinical utility was defined as the ability to improve bone health outcomes with the focus on the average risk population (excluding those with osteoporosis) and patients with kidney disease.
Literature Search
A literature search was performed on July 17th, 2009 using OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published from January 1, 1998 until July 17th, 2009. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any additional relevant studies not identified through the search. Articles with unknown eligibility were reviewed with a second clinical epidemiologist, then a group of epidemiologists until consensus was established. The quality of evidence was assessed as high, moderate, low or very low according to GRADE methodology.
Observational studies that evaluated the prevalence of vitamin D deficiency in Canada in the population of interest were included based on the inclusion and exclusion criteria listed below. The baseline values were used in this report in the case of interventional studies that evaluated the effect of vitamin D intake on serum levels. Studies published in grey literature were included if no studies published in the peer-reviewed literature were identified for specific outcomes or subgroups.
Considering that vitamin D status may be affected by factors such as latitude, sun exposure, food fortification, among others, the search focused on prevalence studies published in Canada. In cases where no Canadian prevalence studies were identified, the decision was made to include studies from the United States, given the similar policies in vitamin D food fortification and recommended daily intake.
Inclusion Criteria
Studies published in English
Publications that reported the prevalence of vitamin D deficiency in Canada
Studies that included subjects from the general population or with kidney disease
Studies in children or adults
Studies published between January 1998 and July 17th 2009
Exclusion Criteria
Studies that included subjects defined according to a specific disease other than kidney disease
Letters, comments, and editorials
Studies that measured the serum vitamin D levels but did not report the percentage of subjects with serum levels below a given threshold
Outcomes of Interest
Prevalence of serum vitamin D less than 25 nmol/L
Prevalence of serum vitamin D less than 40 to 50 nmol/L
Serum 25-hydroxyvitamin D was the metabolite used to assess vitamin D status. Results from adult and children studies were reported separately. Subgroup analyses according to factors that affect serum vitamin D levels (e.g., seasonal effects, skin pigmentation, and vitamin D intake) were reported if enough information was provided in the studies
Quality of Evidence
The quality of the prevalence studies was based on the method of subject recruitment and sampling, possibility of selection bias, and generalizability to the source population. The overall quality of the trials was examined according to the GRADE Working Group criteria.
Summary of Findings
Fourteen prevalence studies examining Canadian adults and children met the eligibility criteria. With the exception of one longitudinal study, the studies had a cross-sectional design. Two studies were conducted among Canadian adults with renal disease but none studied Canadian children with renal disease (though three such US studies were included). No systematic reviews or health technology assessments that evaluated the prevalence of vitamin D deficiency in Canada were identified. Two studies were published in grey literature, consisting of a Canadian survey designed to measure serum vitamin D levels and a study in infants presented as an abstract at a conference. Also included were the results of vitamin D tests performed in community laboratories in Ontario between October 2008 and September 2009 (provided by the Ontario Association of Medical Laboratories).
Different threshold levels were used in the studies, thus we reported the percentage of subjects with serum levels of between 25 and 30 nmol/L and between 37.5 and 50 nmol/L. Some studies stratified the results according to factors affecting vitamin D status and two used multivariate models to investigate the effects of these characteristics (including age, season, BMI, vitamin D intake, skin pigmentation, and season) on serum 25(OH)D levels. It’s unclear, however, if these studies were adequately powered for these subgroup analyses.
Study participants generally consisted of healthy, community-dwelling subjects and most excluded individuals with conditions or medications that alter vitamin D or bone metabolism, such as kidney or liver disease. Although the studies were conducted in different parts of Canada, fewer were performed in Northern latitudes, i.e. above 53°N, which is equivalent to the city of Edmonton.
Serum vitamin D levels of < 25 to 30 nmol/L were observed in 0% to 25.5% of the subjects included in five studies; the weighted average was 3.8% (95% CI: 3.0, 4.6). The preliminary results of the Canadian survey showed that approximately 5% of the subjects had serum levels below 29.5 nmol/L. The results of over 600,000 vitamin D tests performed in Ontarian community laboratories between October 2008 and September 2009 showed that 2.6% of adults (> 18 years) had serum levels < 25 nmol/L.
The prevalence of serum vitamin D levels below 37.5-50 nmol/L reported among studies varied widely, ranging from 8% to 73.6% with a weighted average of 22.5%. The preliminary results of the CHMS survey showed that between 10% and 25% of subjects had serum levels below 37 to 48 nmol/L. The results of the vitamin D tests performed in community laboratories showed that 10% to 25% of the individuals had serum levels between 39 and 50 nmol/L.
In an attempt to explain this inter-study variation, the study results were stratified according to factors affecting serum vitamin D levels, as summarized below. These results should be interpreted with caution as none were adjusted for other potential confounders. Adequately powered multivariate analyses would be necessary to determine the contribution of risk factors to lower serum 25(OH)D levels.
Seasonal variation
Three adult studies evaluating serum vitamin D levels in different seasons observed a trend towards a higher prevalence of serum levels < 37.5 to 50 nmol/L during the winter and spring months, specifically 21% to 39%, compared to 8% to 14% in the summer. The weighted average was 23.6% over the winter/spring months and 9.6% over summer. The difference between the seasons was not statistically significant in one study and not reported in the other two studies.
Skin Pigmentation
Four studies observed a trend toward a higher prevalence of serum vitamin D levels < 37.5 to 50 nmol/L in subjects with darker skin pigmentation compared to those with lighter skin pigmentation, with weighted averages of 46.8% among adults with darker skin colour and 15.9% among those with fairer skin.
Vitamin D intake and serum levels
Four adult studies evaluated serum vitamin D levels according to vitamin D intake and showed an overall trend toward a lower prevalence of serum levels < 37.5 to 50 nmol/L with higher levels of vitamin D intake. One study observed a dose-response relationship between higher vitamin D intake from supplements, diet (milk), and sun exposure (results not adjusted for other variables). It was observed that subjects taking 50 to 400 IU or > 400 IU of vitamin D per day had a 6% and 3% prevalence of serum vitamin D level < 40 nmol/L, respectively, versus 29% in subjects not on vitamin D supplementation. Similarly, among subjects drinking one or two glasses of milk per day, the prevalence of serum vitamin D levels < 40 nmol/L was found to be 15%, versus 6% in those who drink more than two glasses of milk per day and 21% among those who do not drink milk. On the other hand, one study observed little variation in serum vitamin D levels during winter according to milk intake, with the proportion of subjects exhibiting vitamin D levels of < 40 nmol/L being 21% among those drinking 0-2 glasses per day, 26% among those drinking > 2 glasses, and 20% among non-milk drinkers.
The overall quality of evidence for the studies conducted among adults was deemed to be low, although it was considered moderate for the subgroups of skin pigmentation and seasonal variation.
Newborn, Children and Adolescents
Five Canadian studies evaluated serum vitamin D levels in newborns, children, and adolescents. In four of these, it was found that between 0 and 36% of children exhibited deficiency across age groups with a weighted average of 6.4%. The results of over 28,000 vitamin D tests performed in children 0 to 18 years old in Ontario laboratories (Oct. 2008 to Sept. 2009) showed that 4.4% had serum levels of < 25 nmol/L.
According to two studies, 32% of infants 24 to 30 months old and 35.3% of newborns had serum vitamin D levels of < 50 nmol/L. Two studies of children 2 to 16 years old reported that 24.5% and 34% had serum vitamin D levels below 37.5 to 40 nmol/L. In both studies, older children exhibited a higher prevalence than younger children, with weighted averages 34.4% and 10.3%, respectively. The overall weighted average of the prevalence of serum vitamin D levels < 37.5 to 50 nmol/L among pediatric studies was 25.8%. The preliminary results of the Canadian survey showed that between 10% and 25% of subjects between 6 and 11 years (N= 435) had serum levels below 50 nmol/L, while for those 12 to 19 years, 25% to 50% exhibited serum vitamin D levels below 50 nmol/L.
The effects of season, skin pigmentation, and vitamin D intake were not explored in Canadian pediatric studies. A Canadian surveillance study did, however, report 104 confirmed cases1 (2.9 cases per 100,000 children) of vitamin D-deficient rickets among Canadian children age 1 to 18 between 2002 and 2004, 57 (55%) of which from Ontario. The highest incidence occurred among children living in the North, i.e., the Yukon, Northwest Territories, and Nunavut. In 92 (89%) cases, skin pigmentation was categorized as intermediate to dark, 98 (94%) had been breastfed, and 25 (24%) were offspring of immigrants to Canada. There were no cases of rickets in children receiving ≥ 400 IU VD supplementation/day.
Overall, the quality of evidence of the studies of children was considered very low.
Kidney Disease
Two studies evaluated serum vitamin D levels in Canadian adults with kidney disease. The first included 128 patients with chronic kidney disease stages 3 to 5, 38% of which had serum vitamin D levels of < 37.5 nmol/L (measured between April and July). This is higher than what was reported in Canadian studies of the general population during the summer months (i.e. between 8% and 14%). In the second, which examined 419 subjects who had received a renal transplantation (mean time since transplantation: 7.2 ± 6.4 years), the prevalence of serum vitamin D levels < 40 nmol/L was 27.3%. The authors concluded that the prevalence observed in the study population was similar to what is expected in the general population.
No studies evaluating serum vitamin D levels in Canadian pediatric patients with kidney disease could be identified, although three such US studies among children with chronic kidney disease stages 1 to 5 were. The mean age varied between 10.7 and 12.5 years in two studies but was not reported in the third. Across all three studies, the prevalence of serum vitamin D levels below the range of 37.5 to 50 nmol/L varied between 21% and 39%, which is not considerably different from what was observed in studies of healthy Canadian children (24% to 35%).
Overall, the quality of evidence in adults and children with kidney disease was considered very low.
Clinical Utility of Vitamin D Testing
A high quality comprehensive systematic review published in August 2007 evaluated the association between serum vitamin D levels and different bone health outcomes in different age groups. A total of 72 studies were included. The authors observed that there was a trend towards improvement in some bone health outcomes with higher serum vitamin D levels. Nevertheless, precise thresholds for improved bone health outcomes could not be defined across age groups. Further, no new studies on the association were identified during an updated systematic review on vitamin D published in July 2009.
With regards to non-bone health outcomes, there is no high or even moderate quality evidence that supports the effectiveness of vitamin D in outcomes such as cancer, cardiovascular outcomes, and all-cause mortality. Even if there is any residual uncertainty, there is no evidence that testing vitamin D levels encourages adherence to Health Canada’s guidelines for vitamin D intake. A normal serum vitamin D threshold required to prevent non-bone health related conditions cannot be resolved until a causal effect or correlation has been demonstrated between vitamin D levels and these conditions. This is as an ongoing research issue around which there is currently too much uncertainty to base any conclusions that would support routine vitamin D testing.
For patients with chronic kidney disease (CKD), there is again no high or moderate quality evidence supporting improved outcomes through the use of calcitriol or vitamin D analogs. In the absence of such data, the authors of the guidelines for CKD patients consider it best practice to maintain serum calcium and phosphate at normal levels, while supplementation with active vitamin D should be considered if serum PTH levels are elevated. As previously stated, the authors of guidelines for CKD patients believe that there is not enough evidence to support routine vitamin D [25(OH)D] testing. According to what is stated in the guidelines, decisions regarding the commencement or discontinuation of treatment with calcitriol or vitamin D analogs should be based on serum PTH, calcium, and phosphate levels.
Limitations associated with the evidence of vitamin D testing include ambiguities in the definition of an ‘adequate threshold level’ and both inter- and intra- assay variability. The MAS considers both the lack of a consensus on the target serum vitamin D levels and assay limitations directly affect and undermine the clinical utility of testing. The evidence supporting the clinical utility of vitamin D testing is thus considered to be of very low quality.
Daily vitamin D intake, either through diet or supplementation, should follow Health Canada’s recommendations for healthy individuals of different age groups. For those with medical conditions such as renal disease, liver disease, and malabsorption syndromes, and for those taking medications that may affect vitamin D absorption/metabolism, physician guidance should be followed with respect to both vitamin D testing and supplementation.
Studies indicate that vitamin D, alone or in combination with calcium, may decrease the risk of fractures and falls among older adults.
There is no high or moderate quality evidence to support the effectiveness of vitamin D in other outcomes such as cancer, cardiovascular outcomes, and all-cause mortality.
Studies suggest that the prevalence of vitamin D deficiency in Canadian adults and children is relatively low (approximately 5%), and between 10% and 25% have serum levels below 40 to 50 nmol/L (based on very low to low grade evidence).
Given the limitations associated with serum vitamin D measurement, ambiguities in the definition of a ‘target serum level’, and the availability of clear guidelines on vitamin D supplementation from Health Canada, vitamin D testing is not warranted for the average risk population.
Health Canada has issued recommendations regarding the adequate daily intake of vitamin D, but current studies suggest that the mean dietary intake is below these recommendations. Accordingly, Health Canada’s guidelines and recommendations should be promoted.
Based on a moderate level of evidence, individuals with darker skin pigmentation appear to have a higher risk of low serum vitamin D levels than those with lighter skin pigmentation and therefore may need to be specially targeted with respect to optimum vitamin D intake. The cause-effect of this association is currently unclear.
Individuals with medical conditions such as renal and liver disease, osteoporosis, and malabsorption syndromes, as well as those taking medications that may affect vitamin D absorption/metabolism, should follow their physician’s guidance concerning both vitamin D testing and supplementation.
PMCID: PMC3377517  PMID: 23074397
16.  Maternal vitamin D status during pregnancy and child outcomes 
To investigate whether exposure to high maternal concentrations of 25(OH)-vitamin D in pregnancy poses any risk to the child.
Prospective study.
Princess Anne Maternity Hospital, Southampton, UK.
596 pregnant women were recruited. 466 (78%) children were examined at birth, 440 (74%) at age 9 months and 178 (30%) at age 9 years.
Maternal (OH)-vitamin D concentrations were measured in late pregnancy. Anthropometry of the child was recorded at birth, 9 months and 9 years. At 9 months, atopic eczema was assessed. At 9 years, children had an echocardiogram and a DXA scan, blood pressure, arterial compliance and carotid intima-media thickness were measured and intelligence and psychological function assessed.
There were no associations between maternal 25(OH)-vitamin D concentrations and the child's body size or measures of the child's intelligence, psychological health or cardiovascular system. Children whose mothers' concentration of 25(OH)-vitamin D in pregnancy was >75 nmol/l had an increased risk of eczema on examination at 9 months (OR 3.26, 95% CI 1.15-9.29, p=0.025) and asthma at age 9 years (OR 5.40, 95% CI, 1.09-26.65, p=0.038) compared to children whose mothers' concentration was <30 nmol/l.
Exposure to maternal concentrations of 25(OH)-vitamin D in pregnancy in excess of 75 nmol/l does not appear to influence the child's intelligence, psychological health or cardiovascular system; there could be an increased risk of atopic disorders, but this needs confirmation in other studies.
PMCID: PMC2629513  PMID: 17311057
pregnancy; diet; vitamin D; infant; child
17.  Maternal predictors of neonatal bone size and geometry: the Southampton Women’s Survey 
Early growth is associated with later risk of osteoporosis and fractures. In this study, we aimed to evaluate the relationships between maternal lifestyle and body composition and neonatal bone size, geometry and density in the offspring. Participants were recruited from the Southampton Women’s Survey, a unique prospective cohort of 12,500 initially non-pregnant women aged 20–34 years, resident in Southampton, UK. These women were studied in detail before and during pregnancy, and the offspring underwent anthropometric and bone mineral assessment (using dual energy-X-ray absorptiometry) at birth. A total of 841 mother–baby pairs were studied (443 boys and 398 girls). The independent predictors of greater neonatal whole body bone area (BA) and bone mineral content included greater maternal birthweight, height, parity, triceps skinfold thickness and lower walking speed in late pregnancy. Maternal smoking was independently associated with lower neonatal bone mass. Neonatal BA adjusted for birth length (a measure of bone width) was predicted positively by maternal parity and late pregnancy triceps skinfold thickness and negatively by late pregnancy walking speed. These findings were similar in both genders. We have confirmed, in a large cohort, previous findings that maternal lifestyle and body build predict neonatal bone mineral; additionally, maternal parity and fat stores and walking speed in late pregnancy were associated with neonatal bone geometry. These findings may suggest novel public health strategies to reduce the burden of osteoporotic fracture in future generations.
PMCID: PMC3672833  PMID: 23750315
developmental origins; epidemiology; geometry; osteoporosis; programming
18.  Single megadose vitamin A supplementation of Indian mothers and morbidity in breastfed young infants 
Postgraduate Medical Journal  2003;79(933):397-402.
Background and objective: In developing countries low maternal vitamin A stores combined with increased demands of pregnancy and lactation may lead to its deficiency in breastfed infants. This study evaluates the effects of maternal supplementation with a high dose of vitamin A on the serum retinol levels of exclusively breastfed infants, and their morbidity in the first six months of life.
Setting: Hospital based.
Study design: Randomised controlled trial.
Subjects and methods: Mothers of the test group (n=150) were orally supplemented with a single dose of retinol (209 µmol) soon after delivery and were advised exclusive breastfeeding for six months. Before supplementation retinol levels were estimated in the mothers' and newborns' blood, and in colostrum. On follow up, breastmilk and infants' serum retinol contents were assessed monthly for six months. Retinol level <0.7 µmol/l indicated vitamin A deficiency. Morbidity patterns like vitamin A deficiency, diarrhoea, febrile illnesses, acute respiratory infection, measles, and ear infection were also studied and compared between the two groups.
Results: Presupplement mean maternal serum retinol levels were 0.98 and 0.92 µmol/l and mean breastmilk levels were 3.85 and 3.92 µmol/l in the test and control groups respectively (p>0.05). Mean cord blood retinol levels were also comparable (0.68 v 0.64 µmol/l). After supplementation, the test group showed a rise in mean breastmilk retinol content (12.08 v 2.96 µmol/l) which remained significantly higher for four months. The infants' mean serum retinol level, initially 322.06% of the baseline value, was significantly higher for five months. In the control group, significant numbers of mothers and infants showed deficient breastmilk and serum retinol throughout the follow up (p<0.01). Decreased incidence and duration of various diseases were also found in the test group suggesting lesser morbidity.
Conclusion: Maternal supplementation with single megadose vitamin A is an effective strategy for vitamin A prophylaxis of exclusively breastfed infants of 0–6 months.
PMCID: PMC1742755  PMID: 12897218
19.  The Effect of Intermittent Antenatal Iron Supplementation on Maternal and Infant Outcomes in Rural Viet Nam: A Cluster Randomised Trial 
PLoS Medicine  2013;10(6):e1001470.
Beverley-Anne Biggs and colleagues conduct a community-based cluster randomized trial in rural Viet Nam to compare the effect of antenatal iron-folic acid supplementation taken daily or twice weekly on maternal and infant outcomes.
Please see later in the article for the Editors' Summary
Anemia affects over 500 million women, and in pregnancy is associated with impaired maternal and infant outcomes. Intermittent antenatal iron supplementation is an attractive alternative to daily dosing; however, the impact of this strategy on infant outcomes remains unclear. We compared the effect of intermittent antenatal iron supplementation with daily iron supplementation on maternal and infant outcomes in rural Viet Nam.
Methods and Findings
This cluster randomised trial was conducted in Ha Nam province, Viet Nam. 1,258 pregnant women (<16 wk gestation) in 104 communes were assigned to daily iron–folic acid (IFA), twice weekly IFA, or twice weekly multiple micronutrient (MMN) supplementation. Primary outcome was birth weight. Mean birth weight was 3,148 g (standard deviation 416). There was no difference in the birth weights of infants of women receiving twice weekly IFA compared to daily IFA (mean difference [MD] 28 g; 95% CI −22 to 78), or twice weekly MMN compared to daily IFA (MD −36.8 g; 95% CI −82 to 8.2). At 32 wk gestation, maternal ferritin was lower in women receiving twice weekly IFA compared to daily IFA (geometric mean ratio 0.73; 95% CI 0.67 to 0.80), and in women receiving twice weekly MMN compared to daily IFA (geometric mean ratio 0.62; 95% CI 0.57 to 0.68), but there was no difference in hemoglobin levels. Infants of mothers who received twice weekly IFA had higher cognitive scores at 6 mo of age compared to those who received daily IFA (MD 1.89; 95% CI 0.23 to 3.56).
Twice weekly antenatal IFA or MMN did not produce a clinically important difference in birth weight, when compared to daily IFA supplementation. The significant improvement in infant cognitive outcomes at 6 mo of age following twice weekly antenatal IFA requires further exploration, and provides additional support for the use of intermittent, rather than daily, antenatal IFA in populations with low rates of iron deficiency.
Trial registration
Australia New Zealand Clinical Trials Registry 12610000944033
Please see later in the article for the Editors' Summary
Editors' Summary
Anemia is a common condition in which the blood does not supply the body with enough oxygen because of a low number of red blood cells or low levels of hemoglobin—the iron-containing pigment that enables red blood cells to carry oxygen. Iron deficiency is the most common cause of anemia worldwide and, according to the World Health Organization, affects over 2 billion people: half of all pregnant women and 40% of preschool children in low- and middle-income countries are thought to be anemic. Anemia contributes to 20% of all maternal deaths and is also linked to increased maternal morbidity, higher rates of preterm birth and low birth weight, and reduced infant survival, with potential long-term consequences for child growth and development. Identifying and treating iron deficiency anemia is therefore a global health priority.
Why Was This Study Done?
Daily iron–folic acid supplementation given from early in pregnancy is the standard recommended approach to prevent and treat anemia in pregnant women, but recently the World Health Organization recommended intermittent use because of poor compliance with daily regimes (because of side effects) and poor bowel absorption. However, the evidence from many of the studies used to support this recommendation was of poor quality, and so it remains unclear whether intermittent supplementation is as, or more, effective than daily supplementation, especially in lower income settings where antenatal testing for anemia is not readily available. So in this study, the researchers conducted a community-based cluster randomized trial (where groups of people are randomized, rather than individuals) in rural Viet Nam to compare the effect of antenatal iron–folic acid supplementation taken twice weekly (either alone, or in combination with other micronutrients) with daily iron–folic acid supplementation, on maternal and infant outcomes during the first six months of life.
What Did the Researchers Do and Find?
The researchers randomized 104 communes in Ha Nam Province, Viet Nam, and enrolled 1,258 women who were less than 16 weeks pregnant into the study between September and November 2010. Although the researchers intended to register the trial before the study started, registration was delayed by a month because the supplements arrived earlier than the researchers anticipated, and they thought it best to start recruiting at that time to avoid the Vietnamese New Year, when women might be travelling. Each woman was interviewed and had blood taken for hemoglobin and iron indices (ferritin) before receiving daily iron–folic acid supplementation (426 women), twice weekly iron–folic acid supplementation (425 women), or twice weekly iron–folic acid supplementation plus micronutrients (407 women). The women had follow-up assessments at 32 weeks gestation, delivery, and at six months postpartum: their infants were assessed at birth and at six months old.
The researchers found that at enrollment, the women's average hemoglobin concentration was 123 g/l, and 12.6% of the women were anemic. At 32 weeks gestation, 10.8% of the women were anemic, but there was no difference in hemoglobin levels between the three supplement groups. The average ferritin level was 75.6 µg/l at enrollment, with 2.2% of women iron deficient. Ferritin levels decreased from enrollment to 32 weeks gestation in all supplement groups but were lower in women who took twice weekly supplements. The researchers also found that birth weight (the primary outcome) was similar in all supplement groups, and there were also no differences in gestational age or in the risk of prematurity, stillbirth, or early neonatal death. At six months, there were also no differences in the levels of infant hemoglobin, prevalence of anemia, or growth rates. However, infants born to mothers in the twice weekly iron–folic acid group had improved cognitive development compared to infants born to mothers in the daily supplement group. Finally, the researchers found that adherence rates were significantly higher in the twice weekly iron–folic acid supplement group compared to the once daily regime.
What Do These Findings Mean?
These findings suggest that in an area of Southeast Asia with low anemia prevalence, once daily antenatal supplementation with iron–folic acid did not provide any benefits in birth weight or improved infant growth over twice weekly supplementation. Furthermore, twice weekly supplementation with iron–folic acid was associated with improved maternal adherence rates and also improved cognitive development in infants aged six months—a finding that requires further study and provides added support for the use of intermittent iron–folic acid supplementation over daily supplementation.
Additional Information
Please access these websites via the online version of this summary at
The World Health Organization website has comprehensive information on anemia, including a report of global estimates and the guideline Intermittent Iron and Folic Acid Supplementation in Non-Anaemic Pregnant Women
Wikipedia provides information on iron supplementation (note: Wikipedia is a free online encyclopedia that anyone can edit; available in several languages)
PMCID: PMC3708703  PMID: 23853552
20.  Vitamins C and E for prevention of pre-eclampsia in women with type 1 diabetes (DAPIT): a randomised placebo-controlled trial 
Lancet  2010;376(6736):259-266.
Results of several trials of antioxidant use during pregnancy have not shown a reduction in pre-eclampsia, but the effect in women with diabetes is unknown. We aimed to assess whether supplementation with vitamins C and E reduced incidence of pre-eclampsia in women with type 1 diabetes.
We enrolled women from 25 UK antenatal metabolic clinics in a multicentre randomised placebo-controlled trial. Eligibility criteria were type 1 diabetes preceding pregnancy, presentation between 8 weeks' and 22 weeks' gestation, singleton pregnancy, and age 16 years or older. Women were randomly allocated in a 1:1 ratio to receive 1000 mg vitamin C and 400 IU vitamin E (α-tocopherol) or matched placebo daily until delivery. The randomisation sequence was stratified by centre with balanced blocks of eight patients. All trial personnel and participants were masked to treatment allocation. The primary endpoint was pre-eclampsia, which we defined as gestational hypertension with proteinuria. Analysis was by modified intention to treat. This study is registered, ISRCTN27214045.
Between April, 2003, and June, 2008, 762 women were randomly allocated to treatment groups (379 vitamin supplementation, 383 placebo). The primary endpoint was assessed for 375 women allocated to receive vitamins, and 374 allocated to placebo. Rates of pre-eclampsia did not differ between vitamin (15%, n=57) and placebo (19%, 70) groups (risk ratio 0·81, 95% CI 0·59–1·12). No adverse maternal or neonatal outcomes were reported.
Supplementation with vitamins C and E did not reduce risk of pre-eclampsia in women with type 1 diabetes. However, the possibility that vitamin supplementation might be beneficial in women with a low antioxidant status at baseline needs further testing.
The Wellcome Trust.
PMCID: PMC2911677  PMID: 20580423
21.  Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational studies and randomised trials 
Objective To evaluate the breadth, validity, and presence of biases of the associations of vitamin D with diverse outcomes.
Design Umbrella review of the evidence across systematic reviews and meta-analyses of observational studies of plasma 25-hydroxyvitamin D or 1,25-dihydroxyvitamin D concentrations and randomised controlled trials of vitamin D supplementation.
Data sources Medline, Embase, and screening of citations and references.
Eligibility criteria Three types of studies were eligible for the umbrella review: systematic reviews and meta-analyses that examined observational associations between circulating vitamin D concentrations and any clinical outcome; and meta-analyses of randomised controlled trials assessing supplementation with vitamin D or active compounds (both established and newer compounds of vitamin D).
Results 107 systematic literature reviews and 74 meta-analyses of observational studies of plasma vitamin D concentrations and 87 meta-analyses of randomised controlled trials of vitamin D supplementation were identified. The relation between vitamin D and 137 outcomes has been explored, covering a wide range of skeletal, malignant, cardiovascular, autoimmune, infectious, metabolic, and other diseases. Ten outcomes were examined by both meta-analyses of observational studies and meta-analyses of randomised controlled trials, but the direction of the effect and level of statistical significance was concordant only for birth weight (maternal vitamin D status or supplementation). On the basis of the available evidence, an association between vitamin D concentrations and birth weight, dental caries in children, maternal vitamin D concentrations at term, and parathyroid hormone concentrations in patients with chronic kidney disease requiring dialysis is probable, but further studies and better designed trials are needed to draw firmer conclusions. In contrast to previous reports, evidence does not support the argument that vitamin D only supplementation increases bone mineral density or reduces the risk of fractures or falls in older people.
Conclusions Despite a few hundred systematic reviews and meta-analyses, highly convincing evidence of a clear role of vitamin D does not exist for any outcome, but associations with a selection of outcomes are probable.
PMCID: PMC3972415  PMID: 24690624
22.  Decreased Bone Mineral Density in Adults Born with Very Low Birth Weight: A Cohort Study 
PLoS Medicine  2009;6(8):e1000135.
Petteri Hovi and colleagues evaluate skeletal health in 144 adults born preterm with very low birth weight and show that as adults these individuals have significantly lower bone mineral density than do their term-born peers.
Very-low-birth-weight (VLBW, <1,500 g) infants have compromised bone mass accrual during childhood, but it is unclear whether this results in subnormal peak bone mass and increased risk of impaired skeletal health in adulthood. We hypothesized that VLBW is associated with reduced bone mineral density (BMD) in adulthood.
Methods and Findings
The Helsinki Study of Very Low Birth Weight Adults is a multidisciplinary cohort study representative of all VLBW births within the larger Helsinki area from 1978 to 1985. This study evaluated skeletal health in 144 such participants (all born preterm, mean gestational age 29.3 wk, birth weight 1,127 g, birth weight Z score 1.3), and in 139 comparison participants born at term, matched for sex, age, and birth hospital. BMD was measured by dual energy X-ray absorptiometry at age 18.5 to 27.1 y. Adults born with VLBW had, in comparison to participants born at term, a 0.51-unit (95% confidence interval [CI] 0.28–0.75) lower lumbar spine Z score and a 0.56-unit (95% CI 0.34–0.78) lower femoral neck Z score for areal BMD. These differences remained statistically significant after adjustment for the VLBW adults' shorter height and lower self-reported exercise intensity.
Young adults born with VLBW, when studied close to the age of peak bone mass, have significantly lower BMD than do their term-born peers. This suggests that compromised childhood bone mass accrual in preterm VLBW children translates into increased risk for osteoporosis in adulthood, warranting vigilance in osteoporosis prevention.
Please see later in the article for the Editors' Summary
Editors' Summary
Most pregnancies last 40 weeks but some babies arrive earlier than expected. Sadly, babies born before 37 weeks of pregnancy—premature babies—are more likely to die than full-term babies, although recent improvements in neonatal care have increased their chances of survival. Premature babies also often have serious long-term health problems, particularly those born before 32 weeks of pregnancy. Such extremely premature babies have poorly developed internal organs and are usually very small—babies whose birth weight is less than 1,500 g are called very-low-birth-weight (VLBW) babies; the average full-term birth weight is about 3,500 g. Furthermore, their bones are not as well developed as those of full-term babies. The human skeleton initially consists of a soft fibrous material called cartilage. This is gradually transformed into bone by a process called bone mineralization. The last third of pregnancy is a crucial period for bone mineralization although the process continues throughout infancy and childhood. Thus, VLBW babies often have subnormal skeletal mineralization and their accrual of bone mass during childhood is frequently compromised.
Why Was This Study Done?
It is not known whether the childhood bone deficits of VLBW babies persist into adulthood because the first generation of these infants not to die soon after birth is only just reaching adulthood. Peak bone mass is reached in early adulthood (bone mass begins to decrease from the age of 35 years onward) and is an important indicator of whether an individual will develop osteoporosis (thinning of the bones) and be susceptible to bone fractures later in life. If adults with VLBW (about 1% of live births in high-income countries are now VLBW births) do have a subnormal peak bone mass and reduced bone mineral density (BMD), they may be able reduce their risk of developing osteoporosis by eating a healthy diet and exercising regularly. In this study (part of the Helsinki Study of Very Low Birth Weight Adults), the researchers investigate the skeletal health of people who were born with VLBW in the Helsinki area between 1978 and 1985.
What Did the Researchers Do and Find?
The researchers compared the skeletal health of 144 young adults who were born prematurely with VLBW and subnormal BMD with that of 139 age- and sex-matched individuals who were born at term. They measured the BMD of the participants (average age 22.6 years) using “dual energy X-ray absorptiometry” and determined a “Z score” for the spine in the lower back (the lower lumbar spine) and the hip (two sites that are routinely examined in assessments of skeletal health). Z scores indicate whether an individual's BMD is significantly different from the average BMD of healthy age- and sex-matched people; in this study, reduced BMD was defined as a Z score of −1.0 or less. The researchers found that adults born with VLBW had an average Z score of −0.51 at the lower lumbar spine and −0.56 at the hip when compared with the adults born at term. Furthermore, 44% of the VLBW participants but only 26% of the term-born participants had a lumbar spine Z score of −1.0 or less. Adjustment for the shorter height of the VLBW participants slightly reduced these differences in BMD but the differences remained statistically significant.
What Do These Findings Mean?
These findings show that, when studied close to the age of peak bone mass, young adults born with VLBW have a significantly lower BMD than their term-born peers and a 2-fold greater risk of having a lumbar spine Z score of below −1.0; a unit decrease in Z score approximately doubles the risk of bone fractures. Because BMD measurements were only taken at one age, it remains possible, however, that the BMD of the VLBW adults might eventually match that of their full-term peers. Recently born VLBW babies still have a lower than average BMD during their childhood, note the researchers, even though their care has changed since the people included in this study were born. Thus, these findings suggest that people who were VLBW infants should be encouraged to eat food rich in vitamin D and calcium and to do regular weight-bearing exercise throughout their lives to improve their bone health and reduce their risk of developing osteoporosis.
Additional Information
Please access these Web sites via the online version of this summary at
The March of Dimes, a nonprofit organization for pregnancy and baby health, provides information on preterm birth (in English and Spanish)
The Nemours Foundation, another nonprofit organization for child health, also provides information on premature babies (in English and Spanish)
MedlinePlus provides links to other information on premature babies and to information on osteoporosis (in English and Spanish)
The US National Institute of Arthritis and Musculoskeletal and Skin Diseases and the UK National Health Service also provide detailed information on all aspects of osteoporosis
Further details about the Helsinki Study of Very Low Birth Weight Adults are available
PMCID: PMC2722726  PMID: 19707270
23.  Impact of Vitamin D Supplementation during Lactation on Vitamin D Status and Body Composition of Mother-Infant Pairs: A MAVID Randomized Controlled Trial 
PLoS ONE  2014;9(9):e107708.
The optimal vitamin D intake for nursing women is controversial. Deterioration, at least in bone mass, is reported during lactation. This study evaluated whether vitamin D supplementation during lactation enhances the maternal and infant’s vitamin D status, bone mass and body composition.
Design and Methods
After term delivery, 174 healthy mothers were randomized to receive 1200 IU/d (800 IU/d+400 IU/d from multivitamins) or 400 IU/d (placebo+400 IU/d from multivitamins) of cholecalciferol for 6 months while breastfeeding. All infants received 400 IU/d of cholecalciferol. Serum 25-hydroxyvitamin D [25(OH)D], iPTH, calcium, urinary calcium, and densitometry were performed in mother-offspring pairs after delivery, and at 3 and 6 months later.
A total of 137 (79%) (n = 70; 1200 IU/d, n = 67; 400 IU/d) completed the study. 25(OH)D was similar in both groups at baseline (13.7 ng/ml vs. 16.1 ng/ml; P = 0.09) and at 3 months (25.7 ng/ml vs. 24.5 ng/ml; P = 0.09), but appeared higher in the 1200 IU/d group at 6 months of supplementation (25.6 ng/ml vs. 23.1 ng/ml; P = 0.009). The prevalence of 25(OH)D <20 ng/ml was comparable between groups at baseline (71% vs. 64%, P = 0.36) but lower in the 1200 IU/d group after 3 months (9% vs. 25%, P = 0.009) and 6 months (14% vs. 30%, P = 0.03). Maternal and infants’ iPTH, calciuria, bone mass and body composition as well as infants’ 25(OH)D levels were not significantly different between groups during the study. Significant negative correlations were noted between maternal 25(OH)D and fat mass (R = −0.49, P = 0.00001), android fat mass (R = −0.53, P = 0.00001), and gynoid fat mass (R = −0.43, P = 0.00001) after 6 months of supplementation.
Vitamin D supplementation at a dose of 400 IU/d was not sufficient to maintain 25(OH)D >20 ng/ml in nursing women, while 1200 IU/d appeared more effective, but had no effect on breastfed offspring vitamin D status, or changes in the bone mass and the body composition observed in both during breastfeeding.
Trial Registration NCT01506557
PMCID: PMC4169453  PMID: 25232839
24.  The effects of vitamin C supplementation on pre-eclampsia in Mulago Hospital, Kampala, Uganda: a randomized placebo controlled clinical trial 
Oxidative stress plays a role in the pathogenesis of pre-eclampsia. Supplementing women with antioxidants during pregnancy may reduce oxidative stress and thereby prevent or delay the onset pre-eclampsia. The objective of this study was to evaluate the effect of supplementing vitamin C in pregnancy on the incidence of pre-eclampsia, at Mulago hospital, Kampala, Uganda.
This was a (parallel, balanced randomization, 1:1) placebo randomized controlled trial conducted at Mulago hospital, Department of Obstetrics and Gynecology. Participants included in this study were pregnant women aged 15-42 years, who lived 15 km or less from the hospital with gestational ages between 12-22 weeks. The women were randomized to take 1000mg of vitamin C (as ascorbic acid) or a placebo daily until they delivered. The primary outcome was pre-eclamsia. Secondary outcomes were: severe pre-eclampsia, gestational hypertension, preterm delivery, low birth weight and still birth delivery. Participants were 932 pregnant women randomized into one of the two treatment arms in a ratio of 1:1. The participants, the care providers and those assessing the outcomes were blinded to the study allocation.
Of the 932 women recruited; 466 were randomized to the vitamin and 466 to the placebo group. Recruitment of participants was from November 2011 to June 2012 and follow up was up to January 2013. Outcome data was available 415 women in the vitamin group and 418 women in the placebo group.
There were no differences in vitamin and placebo groups in the incidence of pre-eclampsia (3.1% versus 4.1%; RR 0.77; 95% CI: 0.37-1.56), severe pre-eclampsia (1.2% versus 1.0%; RR 1.25; 95% CI: 0.34-4.65), gestational hypertension(7.7% versus 11.5%; RR 0.67; 95% CI: 0.43-1.03), preterm delivery (11.3% versus 12.2%; RR 0.92; 95% CI: 0.63-1.34), low birth weight (11.1% versus 10.3%; RR 1.07; 95% CI: 0.72-1.59) and still birth delivery (4.6% versus 4.5%; RR 1.01; 95% CI: 0.54-1.87).
Supplementation with vitamin C did not reduce the incidence of pre-eclampsia nor did it reduce the adverse maternal or neonatal outcomes. We do not recommend the use of vitamin C in pregnancy to prevent pre-eclampsia.
Trial registration
This study was registered at the Pan African Clinical Trial Registry, PACTR201210000418271 on 25th October 2012.
PMCID: PMC4150937  PMID: 25142305
25.  A double blind randomized controlled trial in neonates to determine the effect of vitamin A supplementation on immune responses: The Gambia protocol 
BMC Pediatrics  2014;14:92.
Vitamin A supplementation significantly reduces all-cause mortality when given between 6–59 months of age, but has a null or detrimental effect when given between 1–5 months. Studies of neonatal vitamin A supplementation conducted across Africa and South Asia have produced conflicting findings. These age-pattern variations might result from immunological interactions between vitamin A supplementation and vaccines. Knowledge on the potential immunological sequelae of human neonatal vitamin A supplementation is so scarce that the foremost aim of this study is to seek indicative data on aspects of immunity likely to be affected by neonatal vitamin A supplementation. The objective of this trial is to test whether human neonatal vitamin A supplementation modulates immune function including improved thymic maturation in infancy and improved systemic immune responses to routine immunization.
In an area of moderate vitamin A deficiency in a peri-urban area of The Gambia, 200 mother–infant pairs were enrolled in a double-blind randomised controlled trial. Within 48 hours of birth, neonates were randomised with stratification by birth weight and sex to receive either an oral dose of 50,000 IU vitamin A or placebo. Expanded Programme of Immunisation birth vaccinations were administered after supplementation, with subsequent vaccinations administered at 8, 12 and 16 weeks of age. A range of immunological outcomes were examined up to 17 weeks of age, with additional morbidity and anthropometry follow-up carried out throughout the first year of life. The primary endpoint of this trial is the frequency of circulating T regulatory (Treg) cells expressing gut homing receptors in infants at 17 week post-supplementation, with secondary outcomes including thymus maturation and B cell immune responses.
Indicative immunological data from this trial (and its Bangladeshi counterpart), will complement the larger randomised controlled trials (conducted in India, Tanzania and Ghana), on the effectiveness and safety of neonatal vitamin A supplementation in improving infant survival. Combined these trials, in addition to the existing trials, will inform policy.
Trial registration NCT01476358
PMCID: PMC4018469  PMID: 24708735
Neonatal; Vitamin A supplementation; Immune responses; Africa; Double blind randomised control trial

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