We describe three birth cohort studies, respectively carried out in 1978/79 and 1994 in Ribeirão Preto, a city located in the most developed region of Brazil, and in 1997/98 in São Luís, a city located in a less developed region. The objective of the present report was to describe the methods used in these three studies, presenting their history, methodological design, objectives, developments, and difficulties faced along 28 years of research. The first Ribeirão Preto study, initially perinatal, later encompassed questions regarding the repercussions of intrauterine development on future growth and chronic adult diseases. The subjects were evaluated at birth (N = 6827), at school age (N = 2861), at the time of recruitment for military service (N = 2048), and at 23/25 years of age (N = 2063). The study of the second cohort, which started in 1994 (N = 2846), permitted comparison of aspects of perinatal health between the two groups in the same region, such as birth weight, mortality and health care use. In 1997/98, a new birth cohort study was started in São Luís (N = 2443), capital of the State of Maranhão. The 1994 Ribeirão Preto cohort and the São Luís cohort are in the second phase of joint follow-up. These studies permit comparative temporal analyses in the same place (Ribeirão Preto 1978/79 and and comparisons of two contrasting populations regarding cultural, economic and sociodemographic conditions (Ribeirão Preto and São Luís).

background: There is evidence that intrauterine growth restriction, resulting in newborn girls that are small for gestational age (SGA), may be related to the onset of polycystic ovary syndrome (PCOS). Thus, we studied whether women born SGA have a higher prevalence of PCOS than women born appropriate for gestational age (AGA).methods: This was a prospective birth cohort study of 384 women born at term between June 1, 1978, and May 31, 1979, in Ribeirão Preto, Brazil. After exclusion, 165 women effectively participated in this study, of whom 43 were SGA and 122 were AGA. The prevalence of PCOS was analysed. At a mean age of 29 years, the women agreed to follow the study protocol, which included: anamnesis, physical examination, serum tests [follicle stimulating hormone, luteinizing hormone, total and free testosterone, dehydroepiandrostenedione sulphate, 17-OH-progesterone, fasting insulin, sex steroid-binding globulin (SHBG) and fasting glucose] and pelvic ultrasound. Data regarding gestational age, birthweight, age at menarche and maternal data were obtained from the files of the cohort. The adjusted relative risk (RR) values of the SGA, insulin resistance, body mass index, maternal smoking and parity variables were analysed using Poisson regression with robust adjustment of variance for the prediction of PCOS.results: The prevalence of PCOS was higher in the SGA group than in the AGA group [adjusted RR ¼ 2.44, 95% CI (1.39-4.28)].Hyperandrogenism was more prevalent in the SGA women than in the AGA women (P ¼ 0.011). Circulating SHBG was lower in the SGA women than in the AGA women (P ¼ 0.041), but fasting insulinemia was similar in both groups.conclusions: The prevalence of PCOS in SGA women was twice as high as in AGA women in our study population.

BackgroundPreterm birth is the main cause of morbidity and mortality during the perinatal period. Classical risk factors are held responsible for only 1/3 of preterm births and no current intervention has produced an appreciable reduction of this event. It is necessary to explore new hypotheses and mechanisms of causality by using an integrated approach, collaboration among research groups and less fragmented theoretical-methodological approaches in order to detect new risk factors and to formulate more effective intervention strategies.MethodsThe study will be conducted on a convenience cohort of Brazilian pregnant women recruited at public and private prenatal health services. A total of 1500 pregnant women in São Luís, and 1500 in Ribeirão Preto, will be invited for an interview and for the collection of biological specimens from the 22nd to the 25th week of gestational age (GA). At the time of delivery they will be reinterviewed. GA will be determined using an algorithm based on two criteria: date of last menstruation (DLM) and obstetric ultrasound (OUS) performed at less than 20 weeks of GA. Illicit drug consumption during pregnancy will be determined using a self-applied questionnaire and the following instruments will be used: perceived stress scale, Beck anxiety scale, screening for depression of the Center of Epidemiological Studies (CES-D), experiences of racial discrimination, social network and social support scale of the Medical Outcomes Study and violence (Abuse Assessment Screening and violence questionnaire of the WHO). Bacterial vaginosis, urinary tract infection and periodontal disease will also be identified. Neuroendocrine, immunoinflammatory and medical intervention hypotheses will be tested. The occurrence of elective cesarean section in the absence of labor will be used as a marker of medical intervention.ConclusionPsychosocial, genetic and infectious mechanisms will be selected, since there are indications that they influence preterm birth (PTB). The studies will be conducted in two Brazilian cities with discrepant socioeconomic conditions. The expectation is to identify risk factors for PTB having a greater predictive power than classically studied factors. The final objective is to propose more effective interventions for the reduction of PTB, which, after being tested, might subsidize health policies.Electronic supplementary materialThe online version of this article (doi:10.1186/1742-4755-11-79) contains supplementary material, which is available to authorized users.

Polycystic ovary syndrome (PCOS) is a multifactorial disorder that arises from interactions between genetic, environmental and intrauterine factors. Small-for-gestational-age (SGA) babies and the daughters of mothers with PCOS represent possible postnatal clinical targets for developmental programming by steroid excess. The presence of excess glucocorticoids and/or androgens during foetal organogenesis and growth might promote changes in gene expression, and these changes might be related to an increase in the risk of PCOS-like reproductive and metabolic disorders in postnatal life, such as rapid growth and weight gain during the first 2 years of life (only in SGA babies), hyperinsulinaemia, adipocyte dysfunction and childhood visceral obesity, premature pubarche and adrenarche (only in SGA babies) and PCOS. In the fourth decade of life, women who have PCOS may be at higher risk for type 2 diabetes mellitus, dyslipidaemia and systemic arterial hypertension, which suggests that these women are also at higher risk for cardiovascular disease during menopause. However, PCOS can also occur in women who were born at appropriate weight for GA or in newborns of women without PCOS, which suggests that genetic variation and environmental factors play important roles in the development and maintenance of PCOS in a population. Genome-wide association studies based on adequate population samples have shown a higher frequency of genetic polymorphisms of the LHCGR, THADA and DENND1A genes in women with PCOS. Genetic studies of PCOS have also included analyses of structural changes in the chromosome based on an assessment of telomere length in single, cross-sectional evaluations, and these studies have produced controversial results. The present narrative review assesses the multifactorial origins of PCOS (including environmental, genetic and intra-uterine factors) and the development of conditions associated with this disorder. It is concluded that although PCOS might originate in the intra-uterine environment through developmental programming by steroid excess, the interaction between genetic and environmental factors is crucial for its appearance. Follow-up studies should be conducted to assess the same populations over their entire lifespans while taking into account different aspects of the pathogenesis of PCOS.Reproduction (2015) 150 R11-R24

BackgroundFew cohort studies have been conducted in low and middle-income countries to investigate non-communicable diseases among school-aged children. This article aims to describe the methodology of two birth cohorts, started in 1994 in Ribeirão Preto (RP), a more developed city, and in 1997/98 in São Luís (SL), a less developed town.MethodsPrevalences of some non-communicable diseases during the first follow-up of these cohorts were estimated and compared. Data on singleton live births were obtained at birth (2858 in RP and 2443 in SL). The follow-up at school age was conducted in RP in 2004/05, when the children were 9-11 years old and in SL in 2005/06, when the children were 7-9 years old. Follow-up rates were 68.7% in RP (790 included) and 72.7% in SL (673 participants). The groups of low (<2500 g) and high (≥ 4250 g) birthweight were oversampled and estimates were corrected by weighting.ResultsIn the more developed city there was a higher percentage of non-nutritive sucking habits (69.1% vs 47.9%), lifetime bottle use (89.6% vs 68.3%), higher prevalence of primary headache in the last 15 days (27.9% vs 13.0%), higher positive skin tests for allergens (44.3% vs 25.3%) and higher prevalence of overweight (18.2% vs 3.6%), obesity (9.5% vs 1.8%) and hypertension (10.9% vs 4.6%). In the less developed city there was a larger percentage of children with below average cognitive function (28.9% vs 12.2%), mental health problems (47.4% vs 38.4%), depression (21.6% vs 6.0%) and underweight (5.8% vs 3.6%). There was no difference in the prevalence of bruxism, recurrent abdominal pain, asthma and bronchial hyperresponsiveness between cities.ConclusionsSome non-communicable diseases were highly prevalent, especially in the more developed city. Some high rates suggest that the burden of non-communicable diseases will be high in the future, especially mental health problems.

BackgroundCesarean section (CS) has been associated with obesity, measured by body mass index (BMI), in some studies. It has been hypothesized that this association, if causal, might be explained by changes in gut microbiota. However, little is known about whether CS is also associated with increased adiposity as measured by indicators other than BMI.Objective: To assess the association between CS and indicators of peripheral and central adiposity in young adults.MethodsThe study was conducted on 2,063 young adults aged 23 to 25 years from the 1978/79Ribeirão Preto birth cohort, São Paulo, Brazil. CS was the independent variable. The anthropometric indicators of adiposity were: waist circumference (WC), waist-height ratio (WHtR), waist-hip ratio (WHR), tricipital skinfold (TSF), and subscapular skinfold (SSF). The association between CS and indicators of adiposity was investigated using a Poisson model, with robust adjustment of variance and calculation of incidence rate ratio (IRR) with 95% confidence interval (95%CI), and adjustment for birth variables.ResultsFollow-up rate was 31.8%. The CS rate was 32%. Prevalences of increased WC, WHtR, WHR were 32.1%, 33.0% and 15.2%, respectively. After adjustment for birth variables, CS was associated with increased risk of adiposity when compared to vaginal delivery: 1.22 (95%CI 1.07; 1.39) for WC, 1.25 (95%CI 1.10;1.42) for WHtR, 1.45 (95%CI 1.18;1.79) for WHR, 1.36 (95%CI 1.04;1.78) for TSF, and 1.43 (95%CI 1.08;1.91) for SSF.ConclusionSubjects born by CS had a higher risk for increased peripheral and central adiposity during young adult age compared to those born by vaginal delivery. The association of CS with adiposity was consistently observed for all indicators and was robust after adjustment for a variety of early life confounders.

CONTEXT AND OBJECTIVE: Alcohol consumption during pregnancy is a significant social problem that may be associated with adverse perinatal outcomes. The aim of this study was to describe alcohol consumption during pregnancy and to study its association with low birth weight, newborns small for gestational age and preterm birth. DESIGN AND SETTING: Nested cohort study, in the city of Ribeirão Preto, São Paulo, Brazil. METHODS: 1,370 women and their newborns were evaluated. A standardized questionnaire on health and lifestyle habits was applied to the mothers. Anthropometry was performed on the newborns. Alcohol consumption was defined as low, moderate or high, as defined by the World Health Organization. Adjusted logistic regression analysis was used. RESULTS: 23% of the women consumed alcohol during pregnancy. Consumption mainly occurred in the first trimester (14.8%) and decreased as the pregnancy progressed. The median alcohol intake was 3.89 g (interquartile range, IQR = 8 g) per day. In the unadjusted analysis, alcohol consumption increased the risk of low birth weight almost twofold (odds ratio, OR 1.91; 95% confidence interval, CI: 1.25-2.92). The risk was lower in the adjusted analysis (OR 1.62; 95% CI: 1.03-2.54). Alcohol consumption did not show associations with small for gestational age or preterm birth. There was greater risk of low birth weight and newborns small for gestational age and preterm birth among mothers who were both smokers and drinkers. CONCLUSIONS: The alcohol consumption rate during pregnancy was 23% and was independently associated with low birth weight, but there was no risk of newborns small for gestational age or preterm birth.RESUMO CONTEXTO E OBJETIVO: O consumo de álcool durante a gravidez é um problema social significativo que pode estar associado a resultados perinatais adversos. O objetivo deste estudo foi descrever o consumo de álcool na gestação e avaliar sua associação com recém-nascido de baixo peso, pequeno para idade gestacional e pré-termo. TIPO DE ESTUDO E LOCAL: Estudo de coorte aninhado, na cidade de Ribeirão Preto, São Paulo, Brasil. MÉTODOS: Foram avaliadas 1.370 mulheres e seus recém-nascidos. Foi aplicado às mães um questionário padronizado sobre saúde e hábitos de vida. Antropometria foi realizada nos recém-nascidos. Consumo de álcool foi definido como baixo, moderado e elevado segundo a Organização Mundial de Saúde. Foi utilizada análise de regressão logística ajustada. RESULTADOS: 23% das gestantes consumiram álcool durante a gravidez. A maior parte do consumo ocorreu no primeiro trimestre (14,8%) e diminuiu conforme progredia a gravidez. A mediana de ingestão de álcool foi de 3,89 g (interval interquartil, IIQ = 8 g) por dia. Na análise não ajustada, o consumo de álcool aumentou em quase duas vezes (odds ratio, OR 1,91, intervalo de confiança, IC 95%; 1,25-2,92) o risco de baixo peso, que se reduziu após ajuste (OR 1,62; IC 95%; 1,03-2,54). Não houve associação entre consumo de álcool e pequeno para idade gestacional ou pré-termo. Observou-se maior r...

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