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 (β: 0.84; 95% CI: 0.55 to 1.12 kg/m(2)), fat mass index (β: 0.44; 95% CI: 0.23 to 0.64 kg/m(2)), android to gynoid fat ratio (β: 0.016; 95% CI: 0.010 to 0.023), waist circumference (β: 1.74; 95% CI: 1.15 to 2.33 cm), waist to height ratio (β: 0.013; 95% CI: 0.010 to 0.017) and lean mass index (β: 0.33; 95% CI: 0.24 to 0.42 kg/m(2)), whereas height was lower (β: −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.