Cesarean section and increased body mass index in school children: two cohort studies from distinct socioeconomic background areas in Brazil
1 Department of Pediatrics, Faculty of Medicine, University of Rio Grande do Sul, Rua Ramiro Barcelos 2350, CEP 90035-903, Porto Alegre, RS, Brazil
2 Department of Pediatrics, Faculty of Medicine of Ribeirao Preto, University of Sao Paulo, Avenida Bandeirantes 3900, Campus USP Monte Alegre, CEP 14049-900, Ribeirao Preto, SP, Brazil
3 Department of Public Health, University of Maranhao, Rua Barão de Itapary 155, Centro, CEP 65020-070, Sao Luis, MA, Brazil
Nutrition Journal 2013, 12:104 doi:10.1186/1475-2891-12-104Published: 25 July 2013
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.
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.
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.
A positive association between cesarean section and increased BMI z-score was demonstrated in areas with different socioeconomic status in a middle-income country.