Parental smoking during pregnancy and risk of overweight and obesity in the daughter.

objectiveEmerging evidence suggests that prenatal exposures may affect long-term health outcomes. In utero exposure to smoking is associated with an increased risk of overweight and obesity in children and adolescents. However, few studies have examined how prenatal exposure to parental smoking influences the risk of obesity during adulthood and whether these associations are independent of childhood and adolescent adiposity. The aim of the current study was to investigate whether prenatal exposure to parental smoking influences body size during adulthood and whether any association may be mediated by childhood and adolescent body size.

methodsWe investigated the association between parental smoking during pregnancy and the risk of being overweight and obese during adulthood and at age 18 and adiposity during childhood among 35 370 participants in the Nurses' Health Study II. Data on smoking during pregnancy and socioeconomic variables were provided by the mothers, and anthropometric data and adult risk factors were reported by participants.

resultsAfter adjustment for socioeconomic and behavioral variables, maternal smoking during pregnancy was associated with adiposity at ages 5-10, 18 and during adulthood. For age 18 overweight, the odd ratios, ORs (95% confidence intervals, CIs) for 1-14, 15-24 and 25+cigarettes per day were 1.13 (1.18-1.50), 1.40 (1.20-1.64) and 1.15 (0.79-1.69), and for obesity were 1.41 (1.14-1.75), 1.69 (1.31-2.18) and 2.36 (1.44-3.86). The corresponding ORs (95% CIs) for obesity during adulthood were 1.26 (1.16-1.37), 1.46 (1.30-1.63) and 1.43 (1.10-1.86). Risk of adiposity was not increased among daughters whose mothers stopped smoking during the first trimester (OR (95% CI) for overweight (1.03 (95% CI 0.90-1.17)) and for obesity (1.12 (95% CI 0.97-1.30)). Women whose fathers smoked during pregnancy were also at an increased risk of being overweight and obese during adulthood with covariate-adjusted ORs (95% CIs) for obesity of 1.19 (1.11-1.29) for 1-14 cigarettes per day, 1.27 (1.18-1.37) for 15-24 cigarettes per day and 1.40 (1.27-1.54) for 25+ cigarettes per day compared with fathers who did not smoke (Ptrend<0.0001). Paternal smoking during pregnancy was also associated with an increased risk of obesity at age 18 among those whose fathers smoked 15 or more cigarettes per day but was not associated with childhood body size.

conclusionsMaternal smoking during pregnancy was associated in a dose-response manner with overweight and obesity in the daughter across adolescence and adult life. Smoking cessation during the first trimester appears to mitigate this excess risk.Paternal smoking was also associated with the risk of being overweight and obese of the adult daughter and this association persisted after adjustment for maternal smoking.