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1.  Cohort Profile update: The 1993 Pelotas (Brazil) Birth Cohort follow-up visits in adolescence 
In this paper we update the profile of the 1993 Pelotas (Brazil) Birth Cohort Study, with emphasis on a shift of priority from maternal and child health research topics to four main categories of outcome variables, collected throughout adolescence: (i) mental health; (ii) body composition; (iii) risk factors for non-communicable diseases (NCDs); (iv) human capital. We were able to trace 81.3% (n = 4106) of the original cohort at 18 years of age. For the first time, the 18-years visit took place entirely on the university premises, in a clinic equipped with state-of-the-art equipment for the assessment of body composition. We welcome requests for data analyses from outside scientists. For more information, refer to our website (http://www.epidemio-ufpel.org.projetos_de_pesquisas/estudos/coorte_1993) or e-mail the corresponding author.
doi:10.1093/ije/dyu077
PMCID: PMC4121560  PMID: 24729426
2.  Happiness and Depression in Adolescence after Maternal Smoking during Pregnancy: Birth Cohort Study 
PLoS ONE  2013;8(11):e80370.
Background
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.
Methodology
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.
​Results
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.
Conclusions
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.
doi:10.1371/journal.pone.0080370
PMCID: PMC3827230  PMID: 24265817
3.  Early life determinants of low IQ at age 6 in children from the 2004 Pelotas Birth Cohort: a predictive approach 
BMC Pediatrics  2014;14(1):308.
Background
Childhood intelligence is an important determinant of health outcomes in adulthood. The first years of life are critical to child development. This study aimed to identify early life (perinatal and during the first year of life) predictors of low cognitive performance at age 6.
Methods
A birth cohort study started in the city of Pelotas, southern Brazil, in 2004 and children were followed from birth to age six. Information on a broad set of biological and social predictors was collected. Cognitive ability—the study outcome—was assessed using the Wechsler Intelligence Scale for Children (WISC). IQ scores were standardized into z-scores and low IQ defined as z < −1. We applied bootstrapping methods for internal validation with a multivariate logistic regression model and carried out external validation using a second study from the 1993 Pelotas Birth Cohort.
Results
The proportion of children with IQ z-score < −1 was 16.9% (95% CI 15.6–18.1). The final model included the following early life variables: child’s gender; parents’ skin color; number of siblings; father’s and mother’s employment status; household income; maternal education; number of persons per room; duration of breastfeeding; height-for-age deficit; head circumference-for-age deficit; parental smoking during pregnancy; and maternal perception of the child’s health status. The area under the ROC curve for our final model was 0.8, with sensitivity of 72% and specificity of 74%. Similar results were found when testing external validation by using data from the 1993 Pelotas Birth Cohort.
Conclusions
The study results suggest that a child’s and her/his family’s social conditions are strong predictors of cognitive ability in childhood. Interventions for promoting a healthy early childhood development are needed targeting children at risk of low IQ so that they can reach their full cognitive potential.
Electronic supplementary material
The online version of this article (doi:10.1186/s12887-014-0308-1) contains supplementary material, which is available to authorized users.
doi:10.1186/s12887-014-0308-1
PMCID: PMC4272809  PMID: 25510879
Child development; Birth cohort; Intelligence; Cognition; Social determinants of health; Brazil
4.  Lifecourse relationship between maternal smoking during pregnancy, birth weight, contemporaneous anthropometric measurements and bone mass at 18 years old. The 1993 Pelotas Birth Cohort 
Early Human Development  2014;90(12):901-906.
Background
Maternal smoking during pregnancy is associated with short-term and also long-term harmful effects on offspring.
Objective
The aim of this study is to evaluate the associations of maternal smoking during pregnancy with offspring bone health at 18 years old, and the role of birth weight and contemporaneous height, weight and body mass index (BMI) in this association.
Data from the 1993 Pelotas Birth Cohort were analyzed using path analysis stratified by sex.
Adolescents at 18 years old (N = 1512 males, 1563 females).
DXA-determined total body bone mineral density (BMD) and bone mineral content (BMC) were assessed at 18 years old.
Results
Each additional cigarette smoked during pregnancy was associated with a lower BMC by − 4.20 g in males (95% CI − 8.37; − 0.05), but not in females [− 2.22 g (95% CI − 5.49; 1.04)]; weaker inverse associations were observed for BMD. This inverse association was explained by the influence of maternal smoking on birth weight and contemporaneous anthropometry, particularly height. A 1 kg higher birth weight was associated with a higher BMC by around 144 g in males and by around 186 g in females, and also with a higher BMD by around 0.019 g/cm2 in males and by around 0.018 g/cm2 in females, respectively.
Conclusions
Lifecourse analysis using path models has enabled to evaluate the role of mediators in the associations of maternal smoking during pregnancy and birth weight with bone mass in the offspring, thus generating improved understanding of the etiology of bone health and the importance of early life experiences.
Highlights
•Each additional cigarette smoked during pregnancy was associated with a lower BMC by − 4.20 g in males at 18 years old.•This inverse association was mediated by birth weight and contemporaneous anthropometry, particularly height.•Birth weight was associated with a higher BMD/BMC in both sexes.
doi:10.1016/j.earlhumdev.2014.08.024
PMCID: PMC4252063  PMID: 25463840
Smoking; Birth weight; Height; Body mass index; Bone mass; Bone density; Bone content; Absorptiometry; Photon; Longitudinal studies; Path analysis; Structural equation model
5.  Risk of childhood undernutrition related to small-for-gestational age and preterm birth in low- and middle-income countries 
Background 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.
Methods Using extant longitudinal birth cohorts (n = 19) with data on birthweight, 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.
Results 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.
Conclusions 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.
doi:10.1093/ije/dyt109
PMCID: PMC3816349  PMID: 23920141
Foetal growth restriction; preterm birth; stunting; wasting; childhood
6.  Antenatal and postnatal maternal mood symptoms and psychiatric disorders in pre-school children from the 2004 Pelotas Birth Cohort 
Journal of Affective Disorders  2014;164(100):112-117.
Background
Maternal mood symptoms have been associated with psychiatric disorders in children. This study aimed to assess critical periods when maternal symptoms would be more deleterious.
Methods
Cohort of 4231 births followed-up in the city of Pelotas, Brazil. Mood symptoms during pregnancy were self-reported by mothers at perinatal interview; and at 3-months postpartum, mothers answered the Self-Reporting Questionnaire. Psychiatric disorders in 6-year-old children were evaluated through the Development and Well-Being Assessment instrument. Odds ratios with 95% confidence intervals (95% CI) were calculated by logistic regression.
Results
Prevalence of mood symptoms in pregnancy was 24.6% (23.2–26.0%) and at three months postpartum 22.5% (21.1–23.9%). Prevalence of mental disorders in children was 13.3% (12.2–14.4%). After adjustment for confounders children of mothers with mood symptoms during pregnancy were 82% more likely of presenting psychiatric disorders than children of mothers that did not (1.82; 1.48–2.25); and the chance of having mental disorders among children whose mothers had positive SRQ-20 at three months postpartum was 87% greater than the observed among children whose mothers had it negative (1.87; 1.50–2.33).
Limitations
Because maternal anxiety/depression may interfere with interpretation of the child behavior, child׳s mental health being obtained by interviewing the mother is a limitation of this study. Lack of information on other risk factors may have lead to residual confounding on the effect of maternal mood symptoms at three months postpartum.
Conclusions
Children of mothers presenting mood symptoms during pregnancy and in the first months postpartum are more likely to present psychiatric disorders at 6 years of age.
doi:10.1016/j.jad.2014.04.033
PMCID: PMC4051989  PMID: 24856563
DAWBA, Development and Well- Being Assessment; EPDS, Edinburgh Post-natal Depression Scale; LBW, low birth weight; LMP, last menstrual period; OR, odds ratio; MW, minimum wages; SRQ-20, self-reporting questionnaire; 95% CI, 95% confidence interval; Mood disorders; Self-reporting questionnaire; Development and Well-Being Assessment; Cohort study; Preschool children
7.  Cohort Profile Update: 2004 Pelotas (Brazil) Birth Cohort Study. Body composition, mental health and genetic assessment at the 6 years follow-up 
International Journal of Epidemiology  2014;43(5):1437-1437f.
This is an update of the 2004 Pelotas Birth Cohort profile, originally published in 2011. In view of the high prevalence of overweight and mental health problems among Brazilian children, together with the availability of state-of-the-art equipment to assess body composition and diagnostic tests for mental health in childhood, the main outcomes measured in the fifth follow-up (mean age 6.8 years) included child body composition, mental health and cognitive ability. A total of 3722 (90.2%) of the original mothers/carers were interviewed and their children examined in a clinic where they underwent whole-body dual X-ray absorptiometry (DXA), air displacement plethysmography and a 3D photonic scan. Saliva samples for DNA were obtained. Clinical psychologists applied the Development and Well-Being Assessment questionnaire and the Wechsler Intelligence Scale for Children to all children. Results are being compared with those of the two earlier cohorts to assess the health effects of economic growth and full implementation of public policies aimed at reducing social inequalities in the past 30 years. For further information visit the programme website at [http://www.epidemio-ufpel.org.br/site/content/coorte_2004/questionarios.php]. Applications to use the data should be made by contacting 2004 cohort researchers and filling in the application form available at [http://www.epidemio-ufpel.org.br/site/content/estudos/formularios.php].
doi:10.1093/ije/dyu144
PMCID: PMC4190519  PMID: 25063002
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.
OBJECTIVE:
To describe the methods employed in the longitudinal and follow-up studies of children born in Pelotas (Southern Brazil) in 1982.
METHODS:
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.
RESULTS:
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).
CONCLUSIONS:
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.  Active Commuting Throughout Adolescence and Central Fatness before Adulthood: Prospective Birth Cohort Study 
PLoS ONE  2014;9(5):e96634.
Background
Active commuting is a good opportunity to accumulate physical activity (PA) across the lifespan that potentially might influence central body fat. We aimed to examine the prospective associations of active commuting at 11, 15 and 18 years of age with central body fat at 18 years.
Methods
Participants were part of a large birth cohort study in Pelotas, Brazil (n = 3,649 participants). Active commuting, leisure-time PA and income were self-reported at 11, 15 and 18 years. Waist circumference and trunk fat mass were collected at 18 years with the use of a 3-dimensional photonic scanner and dual-energy X-ray absorptiometry, respectively.
Results
Active commuting at 11 years was not prospectively associated with central body fat. However, we found that active commuting at 15 and 18 years were prospectively and cross-sectionally associated with central body fat variables, respectively, in boys but not in girls. Also, boys in the highest tertile of accumulated active commuting (i.e., average of active commuting at 11, 13 and 18 years) were associated with −2.09 cm (95%CI: −3.24; −0.94) of waist circumference and −1.11 kg (95%CI: −1.74; −0.48) of trunk fat mass compared to boys in the lowest tertile. Analyses on changes in tertiles of active commuting from 11 and 15 years to 18 years with central body fat variables at 18 years showed that boys who remained consistently in the highest tertile or moved to a higher tertile had lower levels of central body fat compared to those consistently in the lowest tertile.
Conclusions
Active commuting throughout adolescence in boys, especially during middle and late adolescence, is associated with lower levels in central fatness before adulthood.
doi:10.1371/journal.pone.0096634
PMCID: PMC4008595  PMID: 24791780
10.  Prevalence and comorbidity of psychiatric disorders among 6-year-old children: 2004 Pelotas Birth Cohort 
Purpose
Most studies published on the prevalence of psychiatric disorders in children were conducted in high-income countries despite the fact that nearly 90 % of the world’s population aged under 18 live in low- and middle-income countries. The study aimed to assess the prevalence of psychiatric disorders among children of 6 years of age, to examine the distribution of psychiatric disorders by gender and socioeconomic status and to evaluate the occurrence of psychiatric comorbidities.
Methods
The 2004 Pelotas Birth Cohort originally comprised 4,231 live births from Pelotas, southern Brazil. A total of 3,585 (84.7 % of 4,231 births) children aged 6 years were assessed using the Development and Well-Being Assessment (DAWBA).
Results
Nearly 13 % of the children presented a psychiatric diagnosis according to DSM-IV, being more prevalent among males than females (14.7 and 11.7 %, respectively, p = 0.009). Anxiety disorders were the most prevalent of all disorders (8.8 %) and specific phobias (5.4 %) and separation anxiety disorder (3.2 %) were the most common subtypes. Attention deficit hyperactivity disorder (2.6 %), oppositional defiant disorder/conduct disorder (2.6 %), and depression (1.3 %) were also diagnosed. More than one psychiatric disorder was presented by 17 % of children. Socioeconomically disadvantaged children had a higher prevalence of psychiatric disorders.
Conclusion
Our findings underline the early onset of psychiatric disorders among children and the frequent occurrence of psychiatric comorbidity. Early prevention is needed in the field of mental health in Brazil and should start during infancy.
doi:10.1007/s00127-014-0826-z
PMCID: PMC4028510  PMID: 24488152
Prevalence; Cohort studies; Mental disorders; Mental health; Child
11.  Birth Status, Child Growth, and Adult Outcomes in Low- and Middle-Income Countries☆ 
The Journal of Pediatrics  2013;163(6):1740-1746.e4.
Objective
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.
Results
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.
Conclusion
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.
doi:10.1016/j.jpeds.2013.08.012
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
12.  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.
Background
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.
Methods
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.
Results
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.
Conclusions
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.
doi:10.1093/ije/dyt109
PMCID: PMC3816349  PMID: 23920141
Foetal growth restriction; preterm birth; stunting; wasting; childhood
13.  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
14.  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
15.  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.
OBJECTIVE
To describe the patterns of deliveries in a birth cohort and to compare vaginal and cesarean section deliveries.
METHODS
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.
RESULTS
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.
CONCLUSIONS
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.
16.  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.
Background
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.
Results
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.
Conclusion
Caesarean section was associated with a small increased in systolic blood pressure, body mass index and fat mass.
doi:10.1371/journal.pone.0074301
PMCID: PMC3767800  PMID: 24040224
17.  Breast feeding and blood lipid concentrations in male Brazilian adolescents 
Objective
To assess the association between breast feeding and blood lipid levels in adolescence.
Design
Population based prospective birth cohort study.
Setting
City of Pelotas, Brazil.
Subjects
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.
Interventions
None.
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.
Results
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.
Conclusions
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.
doi:10.1136/jech.2005.044156
PMCID: PMC2566240  PMID: 16790835
breast feeding; cholesterol; triglycerides; cohort studies
18.  Breastfeeding duration in two generations 
Revista de saude publica  2007;41(1):13-18.
OBJECTIVE
To assess the intergenerational repetition of breastfeeding duration in a cohort of adolescent mothers who had been prospectively followed up since birth.
METHODS
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.
RESULTS
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)].
CONCLUSIONS
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
19.  Association of family income with BMI from childhood to adult life: a birth cohort study 
Public Health Nutrition  2012;16(2):233-239.
Objective
To investigate the association of family income at birth with BMI among young adults who have been followed since birth.
Design
A birth cohort study.
Setting
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.
Subjects
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.
Results
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.
Conclusions
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.
doi:10.1017/S1368980012003229
PMCID: PMC3541535  PMID: 23102455
BMI; Socio-economic factors; Cohort studies
20.  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
22.  Socioeconomic Trajectories From Birth to Adolescence and Risk Factors for Noncommunicable Disease: Prospective Analyses 
The Journal of Adolescent Health  2012;51(6):S32-S37.
Purpose
To evaluate the associations between family socioeconomic trajectories from 0 to 11 years of age and risk factors for noncommunicable disease at 15 years.
Methods
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.
Results
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.
Conclusions
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.
doi:10.1016/j.jadohealth.2012.06.022
PMCID: PMC3508416  PMID: 23283158
Socioeconomic factors; Poverty; Adolescent; Chronic diseases
23.  Socioeconomic Changes and Adolescent Psychopathology in a Brazilian Birth Cohort Study 
The Journal of Adolescent Health  2012;51(6):S5-S10.
Purpose
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.
Methods
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.
Results
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.
Conclusions
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.
doi:10.1016/j.jadohealth.2012.06.026
PMCID: PMC3508417  PMID: 23283161
Psychopathology; Income; Poverty; Socioeconomic status; Conduct disorders; Emotional disorders; Attention deficit/hyperactivity disorder adolescence
25.  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.
Background
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.
Methods
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.
Results
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.
Conclusion
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.
doi:10.1186/1471-2431-12-169
PMCID: PMC3504558  PMID: 23114098
Gestational age; Preterm births; Early term births; Post-term births; Infant mortality; Neonatal mortality

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