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.

Factors associated with infant and adolescent mortality

Few studies have described factors associated with infant and adolescent mortality since birth. We report here mortality during a 20-year period in a birth cohort from Ribeirão Preto in order to identify birth variables that influenced mortality among infants and children between 10 and 19 years of age, the main causes of death, and the influence of social inequality at birth on death. Mothers were interviewed shortly after delivery. Social, biological and demographic information was collected, and mortality up to 19 years of age was investigated in registry systems. Of the 6748 liveborn singletons born in the municipality from 1978 to 1979, 343 died before or when 19 years of age were completed. Most of the cohort mortality (74.9%) occurred during the first year of life and 19.6% occurred from 10 to 19 years. Mortality was higher among boys. Preterm birth (hazard ratio, HR = 7.94) and low birth weight (HR = 10.15) were strongly associated with infant mortality. Other risk factors for infant mortality were: maternal age (3)35 years (HR = 1.74), unskilled manual occupation of family head (HR = 2.47), and for adolescent mortality: unskilled manual occupation of family head (HR = 9.98) and male sex (HR = 6.58). "Perinatal conditions" were the main causes of deaths among infants and "external causes" among adolescents, especially boys. Socioeconomic factors at birth, represented by occupation, influenced adolescent mortality due to external causes, which was higher among boys (7:1). The influence of social inequality at birth on death, measured by occupation, was greater in adolescence than in infancy.

Health in early adulthood: the contribution of the 1978/79 Ribeirão Preto birth cohort

The increase in non-communicable chronic diseases of adults is due to demographic changes and changes in the risk factors related to physical activity, smoking habits and nutrition. We describe the methodology for the evaluation of persons at 23/25 years of age of a cohort of individuals born in Ribeirão Preto in 1978/79. We present their socioeconomic characteristics and the profile of some risk factors for chronic diseases. A total of 2063 participants were evaluated by means of blood collection, standardized questionnaires, anthropometric and blood pressure measurements, and methacholine bronchoprovocation tests. The sexes were compared by the chi-square test, with alpha = 0.05. Obesity was similar among men and women (12.8 and 11.1%); overweight was almost double in men (30.3 vs 17.7%). Weight deficit was higher among women than among men (8.6 and 2.6%). Women were more sedentary and consumed less alcohol and tobacco. Dietary fat consumption was similar between sexes, with 63% consuming large amounts (30 to 39.9 g/day). Metabolic syndrome was twice more frequent among men than women (10.7 vs 4.8%), hypertension was six times more frequent (40.9 vs 6.4%); altered triglyceride (16.1 vs 9.8%) and LDL proportions (5.4 vs 2.7%) were also higher in men, while women had a higher percentage of low HDL (44.7 vs 39.5%). Asthma and bronchial hyper-responsiveness were 1.7 and 1.5 times more frequent, respectively, among women. The high prevalence of some risk factors for chronic diseases among young adults supports the need for investments in their prevention.