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1.  Happiness and Depression in Adolescence after Maternal Smoking during Pregnancy: Birth Cohort Study 
PLoS ONE  2013;8(11):e80370.
Prenatal cigarette smoke exposure may have adverse psychological effects on offspring. The objective was to assess the association between parental smoking during pregnancy and offspring happiness at age 18, as well as depression.
Participants were part of a birth cohort study in Pelotas, Brazil (5,249 participants). Happiness was measured by the Subjective Happiness Scale, a Likert-like scale with four questions generating a score from 1 to 7, with ≥ 6 indicating "happiness". Depression was measured using the Mini International Psychiatric Interview.
About one third of mothers reported having smoked during pregnancy and 4.6% reported smoking 20 or more cigarettes a day. The prevalence of happiness was 32.2% (95% CI 30.8; 33.7), depression 6.8% (95% CI 6.1; 7.6), and simultaneous happiness and depression less than 1%. The prevalence of offspring happiness decreased as smoking in pregnancy increased, even after control for confounding variables, showing an OR = 0.79 [95% CI 0.55; 1.13]. The opposite happened to depression; the prevalence of offspring depression increased as smoking in pregnancy increased (<20 cigarettes/day OR = 1.38 [95% CI 1.03; 1.84] and ≥20 cigarettes/day OR = 2.11[95% CI 1.31; 3.40]. Smoking by the partner was associated with decreased offspring happiness after adjustment for confounders, but did no show association with offspring depression.
Offspring were less likely to be happy and more likely to be depressed if their mother smoked during pregnancy, and less likely to be happy if their father smoked during mother’s pregnancy. Although we can not affirm that this is a “causal pathway”, public policies to reduce smoking in pregnancy could improve the health of the offspring in the short and long term.
PMCID: PMC3827230  PMID: 24265817
2.  Birth Status, Child Growth, and Adult Outcomes in Low- and Middle-Income Countries☆ 
The Journal of Pediatrics  2013;163(6):1740-1746.e4.
To assess the impact of being born preterm or small for gestational age (SGA) on several adult outcomes.
Study design
We analyzed data for 4518 adult participants in 5 birth cohorts from Brazil, Guatemala, India, the Philippines, and South Africa.
In the study population, 12.8% of males and 11.9% of females were born preterm, and 26.8% of males and 22.4% of females were born term but SGA. Adults born preterm were 1.11 cm shorter (95% CI, 0.57-1.65 cm), and those born term but SGA were 2.35 cm shorter (95% CI, 1.93-2.77 cm) compared with those born at term and appropriate size for gestational age. Blood pressure and blood glucose level did not differ by birth category. Compared with those born term and at appropriate size for gestational age, schooling attainment was 0.44 years lower (95% CI, 0.17-0.71 years) in those born preterm and 0.41 years lower (95% CI, 0.20-0.62 years) in those born term but SGA.
Being born preterm or term but SGA is associated with persistent deficits in adult height and schooling, but is not related to blood pressure or blood glucose level in low- and middle-income settings. Increased postnatal growth is associated with gains in height and schooling regardless of birth status, but not with increases in blood pressure or blood glucose level.
PMCID: PMC3849851  PMID: 24064150
AGA, Appropriate for gestational age; BMI, Body mass index; GA, Gestational age; IFG, Impaired fasting glucose; LGA, Large for gestational age; LMP, Last menstrual period; SGA, Small for gestational age
3.  Risk of childhood undernutrition related to small-for-gestational age and preterm birth in low- and middle-income countries 
International journal of epidemiology  2013;42(5):10.1093/ije/dyt109.
Low- and middle-income countries continue to experience a large burden of stunting; 148 million children were estimated to be stunted, around 30–40% of all children in 2011. In many of these countries, foetal growth restriction (FGR) is common, as is subsequent growth faltering in the first 2 years. Although there is agreement that stunting involves both prenatal and postnatal growth failure, the extent to which FGR contributes to stunting and other indicators of nutritional status is uncertain.
Using extant longitudinal birth cohorts (n = 19) with data on birth-weight, gestational age and child anthropometry (12–60 months), we estimated study-specific and pooled risk estimates of stunting, wasting and underweight by small-for-gestational age (SGA) and preterm birth.
We grouped children according to four combinations of SGA and gestational age: adequate size-for-gestational age (AGA) and preterm; SGA and term; SGA and preterm; and AGA and term (the reference group). Relative to AGA and term, the OR (95% confidence interval) for stunting associated with AGA and preterm, SGA and term, and SGA and preterm was 1.93 (1.71, 2.18), 2.43 (2.22, 2.66) and 4.51 (3.42, 5.93), respectively. A similar magnitude of risk was also observed for wasting and underweight. Low birthweight was associated with 2.5–3.5-fold higher odds of wasting, stunting and underweight. The population attributable risk for overall SGA for outcomes of childhood stunting and wasting was 20% and 30%, respectively.
This analysis estimates that childhood undernutrition may have its origins in the foetal period, suggesting a need to intervene early, ideally during pregnancy, with interventions known to reduce FGR and preterm birth.
PMCID: PMC3816349  PMID: 23920141
Foetal growth restriction; preterm birth; stunting; wasting; childhood
4.  Hospital admissions from birth to early adolescence and early-life risk factors: the 11-year follow-up of the 1993 Pelotas (Brazil) birth cohort study 
Cadernos de saude publica  2010;26(10):1980-1989.
The aim of this prospective analysis was to describe the cumulative incidence of hospital admissions in the first year of life and between 1 and 11 years of age and to explore associated factors. Hospital admissions were collected through regular monitoring in the first year of life, and through maternal report on admissions between 1 and 11 years. Analyses were stratified by sex and adjusted for confounding factors. 18.1% of children were hospitalized in the first year of life, and 30.7% between ages 1 and 11 years. Among boys, hospital admission in the first year was associated with low family income, paternal smoking during pregnancy, preterm delivery, and low birthweight. Among girls, in addition to the variables described for boys, black/mixed skin color was also a risk factor for hospital admission. For admissions between 1 and 11 years of age, low family income and gestational age ≥ 37 weeks were found to be significant risk factors.
PMCID: PMC3795331  PMID: 20963296
Hospitalization; Adolescent; Child; Cohort Studies
5.  Concurrent determinants of blood pressure among adolescents: the 11-year follow-up of the 1993 Pelotas (Brazil) birth cohort study 
Cadernos de saude publica  2010;26(10):1972-1979.
The aim of this study was to evaluate concurrent risk factors for high blood pressure in adolescents. This is a prospective cohort study including 4,452 adolescents born in Pelotas, Rio Grande do Sul State, Brazil, in 1993. Blood pressure was measured before and after the interview, and the mean value was used in the analyses. Mean systolic blood pressure was 101.9mmHg (SD = 12.3) and mean diastolic pressure was 63.4mmHg (SD = 9.9). Adolescents with black skin had higher blood pressure than those with white skin. Mean systolic pressure among subjects in the top quartile of body mass index (BMI) was 11.6mmHg higher than among those in the lowest quartile. Mean systolic pressure among postmenarcheal girls was 5.4mmHg higher than among premenarcheal girls. Similar trends were found for diastolic arterial pressure. Our findings suggest that blood pressure control must begin already in childhood and adolescence.
PMCID: PMC3794424  PMID: 20963295
Blood Pressure; Adolescent; Cohort Studies
6.  Patterns of deliveries in a Brazilian birth cohort: almost universal cesarean sections for the better-off 
Revista de saude publica  2011;45(4):635-643.
To describe the patterns of deliveries in a birth cohort and to compare vaginal and cesarean section deliveries.
All children born to mothers from the urban area of Pelotas, Brazil, in 2004, were recruited for a birth cohort study. Mothers were contacted and interviewed during their hospital stay when extensive information on the gestation, the birth and the newborn, along with maternal health history and family characteristics was collected. Maternal characteristics and childbirth care financing – either private or public healthcare (SUS) patients - were the main factors investigated along with a description of C-sections distribution according to day of the week and delivery time. Standard descriptive techniques, χ2 tests for comparing proportions and Poisson regression to explore the independent effect of C-section predictors were the methods used.
The overall C-section rate was 45%, 36% among SUS and 81% among private patients, where 35% of C-sections were reported elective. C-sections were more frequent on Tuesdays and Wednesdays, reducing by about a third on Sundays, while normal deliveries had a uniform distribution along the week. Delivery time for C-sections was markedly different among public and private patients. Maternal schooling was positively associated with C-section among SUS patients, but not among private patients.
C-sections were almost universal among the wealthier mothers, and strongly related to maternal education among SUS patients. The patterns we describe are compatible with the idea that C-sections are largely done to suit the doctor’s schedule. Drastic action is called for to change the current situation.
PMCID: PMC3794425  PMID: 21670862
Parturition; Cesarean Section, trends; Perinatal Care; Obstetrics; Socioeconomic Factors; Cohort Studies.
7.  Birth by Caesarean Section and Prevalence of Risk Factors for Non-Communicable Diseases in Young Adults: A Birth Cohort Study 
PLoS ONE  2013;8(9):e74301.
Conflicting findings on the risk of obesity among subjects born by caesarean section have been published. Caesarean section should also increase the risk of obesity related cardiovascular risk factors if type of delivery is associated with obesity later in life. This study was aimed at assessing the effect of type of delivery on metabolic cardiovascular risk factors in early adulthood.
Methodology and Principal Findings
In 1982, maternity hospitals in Pelotas, southern Brazil, were visited and those livebirths whose family lived in the urban area of the city have been followed. In 2000, when male subjects undertook the Army entrance examination (n=2200), fat mass and fat free mass were estimated through bioimpedance. In 2004–2005, we attempted to follow the whole cohort (n=4297), and the following outcomes were studied: blood pressure; HDL cholesterol; triglycerides; random blood glucose, C-reactive protein, waist circumference and body mass index. The estimates were adjusted for the following confounders: family income at birth; maternal schooling; household assets index in childhood; maternal skin color; birth order; maternal age; maternal prepregnancy weight; maternal height; maternal smoking during pregnancy; birthweight and family income at early adulthood.
In the crude analyses, blood pressure (systolic, diastolic and mean arterial pressure) and body mass index were higher among subjects who were delivered through caesarean section. After controlling for confounders, systolic blood pressure was 1.15 mmHg (95% confidence interval: 0.05; 2.25) higher among subjects delivered by caesarean section, and BMI 0.40 kg/m2 (95% confidence interval: 0.08; 0.71). After controlling for BMI the effect on systolic blood pressure dropped to 0.60 mmHg (95% confidence interval: -0.47; 1.67). Fat mass at 18 years of age was also higher among subjects born by caesarean section.
Caesarean section was associated with a small increased in systolic blood pressure, body mass index and fat mass.
PMCID: PMC3767800  PMID: 24040224
8.  Methodology of the Pelotas birth cohort study from 1982 to 2004-5, Southern Brazil 
Revista de saude publica  2008;42(Suppl 2):7-15.
To describe the methods employed in the longitudinal and follow-up studies of children born in Pelotas (Southern Brazil) in 1982.
The cohort began with a perinatal health survey that included all 6,011 children born in maternity wards in Pelotas in 1982. The 5,914 children born alive in the city were included in the follow-up studies. By 2004-5, we had conducted eight follow-ups, which consisted of the administration of questionnaires to mothers and/or cohort members, depending on age, in addition to anthropometric and clinical examination. Cohort subjects are described in terms of demographic, socioeconomic, and health-related variables collected during early follow-up studies, which are used as exposure variables.
The majority of subjects in the cohort were followed for 23 years and on multiple occasions. The most successful follow-ups were those preceded by a city census. Using this method, we were able to locate 87.2% of subjects in 1984 (mean age 19 months), 84.1% in 1986 (mean age 43 months), and 77.4% in 2004-5, and 77.4% in 2004-5 (mean age 23 years).
Birth cohort studies can be carried out successfully in developing countries, and the methods employed in this life-cycle study have allowed us to investigate the influence of early exposures in determining disease outcomes in adult life.
PMCID: PMC2671798  PMID: 19142340
Cohort Studies; Epidemiologic Methods; Statistical Methods and Procedures; Child Development; Human Development; Brasil
9.  Breastfeeding duration in two generations 
Revista de saude publica  2007;41(1):13-18.
To assess the intergenerational repetition of breastfeeding duration in a cohort of adolescent mothers who had been prospectively followed up since birth.
All hospital births occurred in Pelotas (N=5,914), a Southern Brazilian city, in 1982 were studied prospectively. The cohort was visited in 1984 and 1986, and information on feeding practices was gathered. In 2001, a search was conducted in the Live Birth Information System and adolescents born in 1982 who gave birth between January 1995 and March 2001 were identified. Parous adolescents answered a detailed questionnaire on pregnancy-related variables and breastfeeding duration for each child. For multiparous adolescents, the information from the first live born child was used. Poisson regression with robust adjustment of the variance was used in the univariate and multivariable analysis.
A total of 446 parous adolescents belonging to the 1982 cohort were identified, of which 420 (94.2%) were interviewed. After adjustment for confounding variables, mothers who had not been breastfed presented a relative risk of 1.34 (95% CI: 0.35; 5.18) of not breastfeeding their children, compared to mothers who were ever breastfed. Similarly, adolescents who were breastfed for less than one month were slightly – but not significantly – more likely to fail to breastfeed their own infants (RR=1.64; 95% CI: 0.70; 4.03). The proportion of adolescent mothers who breastfed for less than six months was higher among those who were themselves breastfed for less than one month (PR=1.29; 95% CI: 1.02; 1.62)].
Duration of breastfeeding is slightly higher among infants whose mother was breastfed.
PMCID: PMC3556507  PMID: 17273629
Breast feeding; Pregnancy in adolescence; Intergenerational relations; Risk factors; Cohort studies; Cohort effects
10.  Association of family income with BMI from childhood to adult life: a birth cohort study 
Public Health Nutrition  2012;16(2):233-239.
To investigate the association of family income at birth with BMI among young adults who have been followed since birth.
A birth cohort study.
In 1982, all children born in Pelotas, southern Brazil, were included in a perinatal survey and visited at ages 1, 2, 4, 15, 18–19 and 23 years.
Cohort members (n 4297) were traced and interviewed in 2004–2005. In all follow-ups, participants were weighed and measured, and BMI and prevalence of obesity were calculated for each age. Family income was obtained in minimum wages in 1982 and as a continuous variable, in reais, in later follow-ups. Skin colour was self-reported in 2004–2005.
Mean BMI and prevalence of obesity differed between males and females. In males, a direct relationship was found throughout life and among females this relationship was modified by age. During childhood, BMI was higher among girls from higher income groups and this association was inversed at age 23 years. At this same age, mean BMI among black women was 1·3 kg/m2 higher than among white women, even after adjustment for current family income.
The findings show in men that the relationship between income and BMI is similar to that seen in less developed areas, whereas among adult women the relationship is similar to that observed in developed countries. In addition to the effect of socio-economic status, skin colour also has an influence on the BMI of adult women.
PMCID: PMC3541535  PMID: 23102455
BMI; Socio-economic factors; Cohort studies
11.  Breastfeeding and feeding patterns in three birth cohorts in Southern Brazil: trends and differentials 
Breastfeeding is fundamental for child health. Changes in the duration of breastfeeding are compared for three population-based cohorts of children born in 1982, 1993 and 2004 in the city of Pelotas, Southern Brazil. Samples of the 1982 and 1993 children and all of the children from the 2004 cohort study were sought at home when they were aged around 12 months. Both the duration of breastfeeding and the stage at which different kind of foods were regularly introduced were investigated. The median duration of breastfeeding increased from 3.1 to 6.8 months in this period. Exclusive breastfeeding at three months was practically non-existent in 1982 and had reached one third of infants by 2004. The increase was faster after 1993, suggesting an important impact made by promotion activities. Up to about 6-9 months, breastfeeding was more prevalent in high-income families, but after this age it became more common among the poor. Low birth weight babies were breastfeed for shorter durations. The duration of breastfeeding is still far short of international recommendations, justifying further campaigns. Special attention should be given to low birth weight babies and those from low-income families.
PMCID: PMC3532951  PMID: 18797716
Breast Feeding; Child Welfare; Cohort Studies
13.  Socioeconomic Trajectories From Birth to Adolescence and Risk Factors for Noncommunicable Disease: Prospective Analyses 
The Journal of Adolescent Health  2012;51(6):S32-S37.
To evaluate the associations between family socioeconomic trajectories from 0 to 11 years of age and risk factors for noncommunicable disease at 15 years.
Individuals born in the city of Pelotas, Brazil, in 1993 are part of a birth cohort study. Socioeconomic position, collected at birth and at 11 years of age, was our main exposure. Risk factors for chronic disease were collected at 15 years. Body mass index was transformed into Z score using the World Health Organization standard. Transport and leisure-time physical activity, smoking, and alcohol consumption were assessed by self-report. Blood pressure was measured using a digital sphygmomanometer.
Of 5,249 cohort members, 85.7% were located at the 15-year follow-up visit. Rich adolescents were more likely to be overweight, be obese, and not use active modes of transport to school. Poor adolescents were more likely to smoke. In relation to socioeconomic trajectories, the odds of obesity were 46% higher among those who were “always rich” compared with those who were “always poor”; the odds of use of an inactive mode of transportation were 326% greater among the “always rich” than the “always poor,” whereas the reverse was observed for smoking (odds of 200%). The “always rich” had one-half the odds of walking or cycling to school compared with those who became wealthy in the studied period.
Adolescent socioeconomic position is a stronger determinant of risk factors for noncommunicable diseases than socioeconomic trajectories. However, trajectories do matter, particularly in terms of use of active transportation to school.
PMCID: PMC3508416  PMID: 23283158
Socioeconomic factors; Poverty; Adolescent; Chronic diseases
14.  Socioeconomic Changes and Adolescent Psychopathology in a Brazilian Birth Cohort Study 
The Journal of Adolescent Health  2012;51(6):S5-S10.
To investigate the effects of socioeconomic changes from birth to 11 years of life on emotional, conduct, and attentional/hyperactivity problems in 15-year-old adolescents, from the 1993 Pelotas (Brazil) birth cohort study.
The original cohort was composed of 5,249 hospital-born children whose mothers answered a questionnaire. We conducted interviews with 87.5% and 85.7% of the original cohort in 2004–2005 and 2008, respectively. We divided family income changes into nine possible categories based on two assessment points (birth and 11 years of age) and three income levels. To assess the psychopathology of the adolescents at 15 years of age, 4,423 mothers answered the Strengths and Difficulties Questionnaire.
Adolescents who were always poor or who became poor between birth and 11 years of age had greater conduct problems at 15 years of age. There was no consistent association between poverty and emotional and attentional/hyperactivity problems.
The effects of income change were more specific to conduct problems than to emotional and attentional/hyperactivity problems, similar to what has been previously described in developed countries.
PMCID: PMC3508417  PMID: 23283161
Psychopathology; Income; Poverty; Socioeconomic status; Conduct disorders; Emotional disorders; Attention deficit/hyperactivity disorder adolescence
16.  Gestational age at birth and morbidity, mortality, and growth in the first 4 years of life: findings from three birth cohorts in Southern Brazil 
BMC Pediatrics  2012;12:169.
We assessed anthropometric status, breastfeeding duration, morbidity, and mortality outcomes during the first four years of life according to gestational age, in three population-based birth cohorts in the city of Pelotas, Southern Brazil.
Total breastfeeding duration, neonatal mortality, infant morbidity and mortality, and anthropometric measures taken at 12 and 48 months were evaluated in children of different gestational ages born in 1982, 1993 and 2004 in Southern Brazil.
Babies born <34 weeks of gestation and those born between 34–36 weeks presented increased morbidity and mortality, were breastfed for shorter periods, and were more likely to be undernourished at 12 months of life, in comparison with the 39–41 weeks group. Children born with 37 weeks were more than twice as likely to die in the first year of life, and were also at increased risk of hospitalization and underweight at 12 months of life. Post-term infants presented an increased risk of neonatal mortality.
The increased risks of morbidity and mortality among preterm (<37 weeks of gestation) and post-term (>41 weeks) are well known. In our population babies born at 37 also present increased risk. As the proportion of preterm and early term babies has increased markedly in recent years, this is a cause for great concern.
PMCID: PMC3504558  PMID: 23114098
Gestational age; Preterm births; Early term births; Post-term births; Infant mortality; Neonatal mortality
17.  Breast feeding and blood lipid concentrations in male Brazilian adolescents 
To assess the association between breast feeding and blood lipid levels in adolescence.
Population based prospective birth cohort study.
City of Pelotas, Brazil.
All hospital births taking place in 1982; 79% of all males (n = 2250) were followed up for 18 years, and 2089 blood samples were available.
Main outcome measures
Total cholesterol and fractions (very low density lipoprotein cholesterol (VLDL), low density lipoprotein cholesterol (LDL), high density lipoprotein cholesterol (HDL)), LDL/HDL ratio, serum triglycerides.
Three breast feeding variables were studied: total duration of breast feeding, duration of exclusive or predominant breast feeding, and ever compared with never breast fed. Adjusted analyses were controlled for family income, household assets index, maternal education, maternal pre‐pregnancy body mass index (BMI), skin colour, birth weight, gestational age, maternal smoking during pregnancy, and adolescent BMI, and behavioural variables (fat content of diet, physical activity, smoking, and alcohol drinking). Only one association reached borderline significance (p = 0.05): LDL cholesterol was slightly higher among never (mean 41.0 mg/dl; 95% CI 39.4 to 42.7) than among ever breast fed men (38.6 mg/dl; 95% CI 38.6 to 40.3), in the adjusted analyses. All other associations were not significant (p⩾0.09). There was no evidence of effect modification according to preterm status, intrauterine growth retardation, socioeconomic level, growth velocity in the first two years of life, or nutritional status at 2 years of age.
There was no clear association between breast feeding duration and serum lipid concentrations at the age of 18 years in this sample of Brazilian men.
PMCID: PMC2566240  PMID: 16790835
breast feeding; cholesterol; triglycerides; cohort studies
18.  Infant-feeding patterns and cardiovascular risk factors in young adulthood: data from five cohorts in low- and middle-income countries 
Background Infant-feeding patterns may influence lifelong health. This study tested the hypothesis that longer duration of breastfeeding and later introduction of complementary foods in infancy are associated with reduced adult cardiovascular risk.
Methods Data were pooled from 10 912 subjects in the age range of 15–41 years from five prospective birth-cohort studies in low-/middle-income countries (Brazil, Guatemala, India, Philippines and South Africa). Associations were examined between infant feeding (duration of breastfeeding and age at introduction of complementary foods) and adult blood pressure (BP), plasma glucose concentration and adiposity (skinfolds, waist circumference, percentage body fat and overweight/obesity). Analyses were adjusted for maternal socio-economic status, education, age, smoking, race and urban/rural residence and infant birth weight.
Results There were no differences in outcomes between adults who were ever breastfed compared with those who were never breastfed. Duration of breastfeeding was not associated with adult diabetes prevalence or adiposity. There were U-shaped associations between duration of breastfeeding and systolic BP and hypertension; however, these were weak and inconsistent among the cohorts. Later introduction of complementary foods was associated with lower adult adiposity. Body mass index changed by −0.19 kg/m2 [95% confidence interval (CI) −0.37 to −0.01] and waist circumference by −0.45 cm (95% CI −0.88 to −0.02) per 3-month increase in age at introduction of complementary foods.
Conclusions There was no evidence that longer duration of breastfeeding is protective against adult hypertension, diabetes or overweight/adiposity in these low-/middle-income populations. Further research is required to determine whether ‘exclusive’ breastfeeding may be protective. Delaying complementary foods until 6 months, as recommended by the World Health Organization, may reduce the risk of adult overweight/adiposity, but the effect is likely to be small.
PMCID: PMC3043278  PMID: 20852257
Infant feeding; breastfeeding; complementary feeding; blood pressure; diabetes; body composition
19.  Cesarean section and risk of obesity in childhood, adolescence, and early adulthood: evidence from 3 Brazilian birth cohorts123 
Background: The number of cesarean sections (CSs) is increasing in many countries, and there are concerns about their short- and long-term effects. A recent Brazilian study showed a 58% higher prevalence of obesity in young adults born by CS than in young adults born vaginally. Because CS-born individuals do not make contact at birth with maternal vaginal and intestinal bacteria, the authors proposed that this could lead to long-term changes in the gut microbiota that could contribute to obesity.
Objective: We assessed whether CS births lead to increased obesity during childhood, adolescence, and early adulthood in 3 birth cohorts.
Design: We analyzed data from 3 birth-cohort studies started in 1982, 1993, and 2004 in Southern Brazil. Subjects were assessed at different ages until 23 y of age. Poisson regression was used to estimate prevalence ratios with adjustment for ≤15 socioeconomic, demographic, maternal, anthropometric, and behavioral covariates.
Results: In the crude analyses, subjects born by CS had ∼50% higher prevalence of obesity at 4, 11, and 15 y of age but not at 23 y of age. After adjustment for covariates, prevalence ratios were markedly reduced and no longer significant for men or women. The only exception was an association for 4-y-old boys in the 1993 cohort, which was not observed in the other 2 cohorts or for girls.
Conclusion: In these 3 birth cohorts, CSs do not seem to lead to an important increased risk of obesity during childhood, adolescence, or early adulthood.
PMCID: PMC3260073  PMID: 22237058
20.  Childbearing during adolescence and offspring mortality: findings from three population-based cohorts in southern Brazil 
BMC Public Health  2011;11:781.
The role of young maternal age as a determinant of adverse child health outcomes is controversial, with existing studies providing conflicting results. This work assessed the association between adolescent childbearing and early offspring mortality in three birth cohort studies from the city of Pelotas in Southern Brazil.
All hospital births from 1982 (6,011), 1993 (5,304), and 2004 (4,287) were identified and these infants were followed up. Deaths were monitored through vital registration, visits to hospitals and cemeteries. The analyses were restricted to women younger than 30 years who delivered singletons (72%, 70% and 67% of the original cohorts, respectively). Maternal age was categorized into three groups (< 16, 16-19, and 20-29 years). Further analyses compared mothers aged 12-19 and 20-29 years. The outcome variables included fetal, perinatal, neonatal, postneonatal and infant mortality. Crude and adjusted odds ratios (ORs) were estimated with logistic regression models.
There were no interactions between maternal age and cohort year. After adjustment for confounding, pooled ORs for mothers aged 12-19 years were 0.6 (95% CI = 0.4; 1.0) for fetal death, 0.9 (0.6; 1.3) for perinatal death, 1.0 (0.7; 1.6) for early neonatal death, 1.6 (0.7; 3.4) for late neonatal death, 1.8 (1.1; 2.9) for postneonatal death, and 1.6 (1.2; 2.1) for infant death, when compared to mothers aged 20-29 years. Further adjustment for mediating variables led to the disappearance of the excess of postneonatal mortality. The number of mothers younger than 16 years was not sufficient for most analyses.
The slightly increased odds of postneonatal mortality among children of adolescent mothers suggest that social and environmental factors may be more important than maternal biologic immaturity.
PMCID: PMC3207956  PMID: 21985467
pregnancy in adolescence; infant mortality; neonatal mortality; perinatal mortality; fetal mortality; cohort studies
21.  Maternal smoking during pregnancy and offspring growth in childhood: 1993 and 2004 Pelotas cohort studies 
Archives of Disease in Childhood  2011;96(6):519-525.
To explore the effects of maternal smoking during pregnancy on offspring growth using three approaches: (1) multiple adjustments for socioeconomic and parental factors, (2) maternal–paternal comparisons as a test of putative intrauterine effects and (3) comparisons between two birth cohort studies.
Population-based birth cohort studies were carried out in Pelotas, Brazil, in 1993 and 2004. Cohort members were followed up at 3, 12, 24 and 48 months. Multiple linear regression analysis was used to examine the relationships between maternal and paternal prenatal smoking and offspring anthropometric indices. In the 2004 cohort, the association of smoking with trunk length, leg length and leg-to-sitting-height ratio at 48 months was also explored.
Maternal smoking during pregnancy was associated with reduced z scores of length/height-for-age at each follow-up in both cohorts and reduced leg length at 48 months in the 2004 cohort. Children older than 3 months born to smoking women showed a higher body mass index-for-age z score than children of non-smoking women.
The results of this study strongly support the hypothesis that maternal smoking during pregnancy impairs linear growth and promotes overweight in childhood.
PMCID: PMC3093240  PMID: 21377989
22.  Adolescent blood pressure, body mass index and skin folds: sorting out the effects of early weight and length gains 
Although there is longstanding evidence of the short-term benefits of promoting rapid growth for young children in low-income settings, more recent studies suggest that early weight gain can also increase the risk of chronic diseases in adults. This paper attempts to separate the effects of early life weight and length/height gains on blood pressure, body mass index (BMI), sum of skin folds and subscapular/triceps skin fold ratio at 14–15 years of age.
The sample comprised 833 members of a prospective population-based birth cohort from Brazil. Conditional size (weight or height) analyses were used to express the difference between observed size at a given age and expected size based on a regression, including all previous measures of the same anthropometric index. A positive conditional weight or height indicates growing faster than expected given prior size.
Conditional weights at all age ranges were positively associated with most outcomes; each z-score of conditional weight at 4 years was associated with an increase of 6.1 mm in the sum of skin folds (95% CI 4.5 to 7.6) in adolescence after adjustment for conditional length/height. Associations of the outcomes with conditional length/height were mostly negative or non-significant—each z-score was associated with a reduction of 2.4 mm (95% CI −3.8 to −1.1) in the sum of skin folds after adjustment for conditional weight. No associations were found with the skin fold ratio.
The promotion of rapid length/height gain without excessive weight gain seems to be beneficial for long-term outcomes, but this requires confirmation from other studies.
PMCID: PMC3245895  PMID: 21325148
Blood pressure; chronic disease; cohort studies; prospective studies; skinfold thickness; adolescents cg; blood pressure; children; chronic DI; cohort me
23.  Weight Gain in the First Two Years of Life Is an Important Predictor of Schooling Outcomes in Pooled Analyses from Five Birth Cohorts from Low- and Middle-Income Countries12 
The Journal of Nutrition  2010;140(2):348-354.
Schooling predicts better reproductive outcomes, better long-term health, and increased lifetime earnings. We used data from 5 cohorts (Brazil, Guatemala, India, the Philippines, and South Africa) to explore the relative importance of birthweight and postnatal weight gain for schooling in pooled analyses (n = 7945) that used appropriate statistical methods [conditional weight (CW) gain measures that are uncorrelated with prior weights] and controlled for confounding. One SD increase in birthweight, ∼0.5 kg, was associated with 0.21 y more schooling and 8% decreased risk of grade failure. One SD increase in CW gain between 0 and 2 y, ∼0.7 kg, was associated with higher estimates, 0.43 y more schooling, and 12% decreased risk of failure. One SD increase of CW gain between 2 and 4 y, ∼0.9 kg, was associated with only 0.07 y more schooling but not with failure. Also, in children born in the lowest tertile of birthweight, 1 SD increase of CW between 0 and 2 y was associated with 0.52 y more schooling compared with 0.30 y in those in the upper tertile. Relationships with age at school entry were inconsistent. In conclusion, weight gain during the first 2 y of life had the strongest associations with schooling followed by birthweight; weight gain between 2 and 4 y had little relationship to schooling. Catch-up growth in smaller babies benefited schooling. Nutrition interventions aimed at women and children under 2 y are among the key strategies for achieving the millennium development goal of universal primary education by 2015.
PMCID: PMC2806888  PMID: 20007336
25.  Long-Lasting Maternal Depression and Child Growth at 4 Years of Age: A Cohort Study 
The Journal of Pediatrics  2010;157(3-3):401-406.
To investigate the association between sustained maternal depression at 12, 24, and 48 months post-partum and child anthropometry at age of 4 years.
Study design
A total of 99.2% of the 4287 children born in 2004 in Pelotas, Brazil, were enrolled in a cohort study. At 3, 12, 24, and 48 months, mothers were interviewed and provided information on several characteristics. Maternal depression was investigated through the Edinburgh Postnatal Depression Scale (EPDS). Weight-for-age, height-for-age, and weight-for-height z-scores at 48 months, according to World Health Organization growth curves, were the outcomes. Multivariate analyses were conducted through logistic regression.
At the 48-month follow-up, of the 3792 children, prevalence of underweight was 1.7%; stunting, 3.6%; wasting, 0.6%; and overweight, 12.2%. Depression (EPDS ≥13) was observed in 17.9% of the 3748 mothers. Of the mothers, 4.7% were persistently depressed at the 12-, 24-, and 48-month visits. In crude analyses, maternal depression was positively associated with underweight and stunting. After adjustment, maternal depression was not associated with any of the anthropometric indices.
Long-lasting maternal depression at 12, 24, and 48 months post-partum is not a risk factor for impaired child growth or overweight at age of 4 years.
PMCID: PMC2937222  PMID: 20400093
BMI, Body mass index; EPDS, Edinburgh Postnatal Depression Scale; GA, Gestational age; H/A, Height-for-age; LBW, Low birth weight; LMP, Last menstrual period; W/A, Weight-for-age; W/H, Weight-for-height; WHO, World Health Organization

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