Cesarean delivery and metabolic risk factors in young adults: a Brazilian birth cohort study.

BACKGROUND: Cesarean delivery (CD) perturbs the assembly of the neonatal gut microbiome and has been associated with child and adult obesity. However, it is still unknown whether CD is associated with metabolic risk factors in young adults. OBJECTIVE: We investigated the association of CD and metabolic risk factors in young adults in a cohort study who were 23-25 y of age at follow-up. DESIGN: We used data from a cohort study in Ribeirão Preto, Brazil. Baseline data on 6827 singleton pregnancies were collected in 1978-1979, and a sample of 2063 subjects were followed up 23-25 y later (2002-2004). Information on the type of delivery, birth weight, maternal age, parity, maternal schooling, and maternal smoking was obtained after birth. Anthropometric data, biochemical measurements, and information on participant schooling and smoking history were collected at 23-25 y of age. A linear regression was performed to assess the association between CD and biochemical measurements in early adulthood, controlling for a minimum set of confounders that were identified in a directed acyclic graph. RESULTS: The mean ± SD age of the subjects was 23.9 ± 0.71 y, and 51.8% of the sample were women. The CD rate was 32.0% and was more common in older (P < 0.001) and more educated mothers (P < 0.001). Compared with vaginal delivery, CD was associated with higher body mass index (BMI) after multivariable adjustment (P < 0.001) but not with glucose, homeostasis model assessment of insulin resistance, the quantitative insulin-sensitivity check index, total cholesterol, LDL cholesterol, HDL cholesterol, or triglycerides (all P > 0.05). CONCLUSION: In our sample of Brazilian adults, CD was associated with higher BMI but not with other metabolic risk factors.

Cesarean section and increased body mass index in school children: two cohort studies from distinct socioeconomic background areas in Brazil.

BACKGROUND: Recent studies have raised controversy regarding the association between cesarean section and later obesity in the offspring. The purpose of this study was to assess the association of cesarean section with increased body mass index (BMI) and obesity in school children from two Brazilian cities with distinct socioeconomic backgrounds. METHODS: Two birth cohorts respectively born in 1994 in Ribeirao Preto, a wealthy city in Southeast, and in 1997/98 in Sao Luis, a less wealthy city in Northeast of Brasil, were evaluated. After birth, 2,846 pairs of mothers-newborns were evaluated in Ribeirao Preto and 2,542 in Sao Luis. In 2004/05, 790 children aged 10/11 years were randomly reassessed in Ribeirao Preto and 673 at 7/9 years in Sao Luis. Information on type of delivery, maternal and child characteristics, socioeconomic position and anthropometric measurements were collected after birth and at school age. Obesity was defined as BMI ≥ 95th percentile at school age. RESULTS: Obesity rate was 13.0% in Ribeirao Preto and 2.1% in Sao Luis. Cesarean section was associated with obesity and remained significant after adjustment only in Ribeirao Preto [OR = 1.74 (95% CI: 1.04; 2.92)]. The association between cesarean section and BMI remained significant after adjustment for maternal schooling, maternal smoking during pregnancy, duration of breastfeeding, gender, birth weight and gestational age, type of school and, only in Sao Luis, pre-pregnancy maternal weight. In Ribeirao Preto children born by cesarean section had BMI 0.31 kg/m2 (95% CI: 0.11; 0.51) higher than those born by vaginal delivery. In Sao Luis BMI of children born by cesarean section was 0.28 kg/m2 higher (95% CI: 0.08; 0.49) than those born by vaginal delivery. CONCLUSION: A positive association between cesarean section and increased BMI z-score was demonstrated in areas with different socioeconomic status in a middle-income country.

Respiratory effects of tobacco smoking among young adults.

BACKGROUND: Respiratory symptoms associated with smoking habit seem to be age dependent. However, there are few reports about the effect of tobacco in young populations. The objective of this study was to analyze the effect of smoking on respiratory symptoms and lung function in 23- to 25-year-old adults in Brazil. This study had a cross-sectional design and included 2063 young people in the city of Ribeirão Preto, São Paulo State. METHODS: Subjects completed a questionnaire used by the European Community Respiratory Health Survey and underwent spirometry and bronchial challenge test with methacholine. Multiple logistic regression analysis and multiple linear regression analysis were carried out to assess the association between smoking and respiratory symptoms, bronchial hyperresponsiveness, forced expiratory volume in 1 second (FEV1), and forced vital capacity (FVC), adjusted for confounding variables. RESULTS: Prevalence of smoking habit was 17.2% with consumption (median) of 10 cigarettes per day (interquartile range 3-20). There was a significant association between smoking and respiratory symptoms. Smoking was associated to wheezing with odds ratio (95%CI) of 6.11 (4.03-9.28) among those smoking>or=10 cigarettes per day and 3.36 (2.11-5.37) among those smoking<10 cigarettes per day. Associations were found for other respiratory symptoms. Smoking was associated with lower FEV1/FVC ratio. No association was detected between smoking and FEV1 or bronchial hyperresponsiveness. CONCLUSIONS: These findings highlight the early health consequences of smoking among young adults. These results prompt the necessity to elaborate urgent programs to reduce tobacco habit in young populations.