Maternal smoking during pregnancy and offspring body composition in adulthood: Results from two birth cohort studies

Objective To evaluate the association of maternal smoking during pregnancy with offspring body composition in adulthood and explore the causality of this association. Design Birth cohort. Setting Population-based study in Pelotas, Brazil. Participants All newborn infants in the city's hospitals were enrolled in 1982 and 1993. At a mean age of 30.2 and 22.6 years, the 1982 and 1993 cohorts, respectively, followed the subjects and 7222 subjects were evaluated. Primary outcome measures Body mass index (BMI), fat mass index, android to gynoid fat ratio, waist circumference, waist to height ratio, lean mass index and height. Results Prevalence of maternal smoking during pregnancy was 35.1% and 32.6%, in 1982 and 1993 cohorts, respectively. Offspring of smoking mothers showed higher mean BMI (beta: 0.84; 95% CI: 0.55 to 1.12 kg/m(2)), fat mass index (beta: 0.44; 95% CI: 0.23 to 0.64 kg/m(2)), android to gynoid fat ratio (beta: 0.016; 95% CI: 0.010 to 0.023), waist circumference (beta: 1.74; 95% CI: 1.15 to 2.33 cm), waist to height ratio (beta: 0.013; 95% CI: 0.010 to 0.017) and lean mass index (beta: 0.33; 95% CI: 0.24 to 0.42 kg/m(2)), whereas height was lower (beta: -0.95; -1.26 to -0.65). Weight gain in the first 2 years captured most of the association of maternal smoking with BMI (96.2%), waist circumference (86.1%) and fat mass index (71.7%). Conclusions Maternal smoking in pregnancy was associated with offspring body composition measures in adulthood.