Background: Maternal smoking during pregnancy may adversely affect bone health in later life. By comparing the associations of maternal and paternal smoking and of prenatal and postnatal exposure with childhood bone measures we aimed to explore whether the suggested association could be explained by foetal programming or reflects confounding by familial factors.
Methods: In 5,565 mothers, fathers, and children participating in a population-based prospective cohort study, parental smoking habits during pregnancy and current household smoking habits were assessed by postal questionnaires. Total body bone mineral content (BMC), bone area (BA) and bone mineral density (BMD) were measured by dual-energy X-ray absorptiometry (DXA) at the median age of 6.0 (IQR 0.37) years.
Results: In confounder adjusted models, maternal smoking during pregnancy was associated with a 11.6 g (95% CI 5.6, 17.5) higher BMC, a 9.7 cm2 (95% CI 3.0, 16.4) larger BA, a 6.7 g/cm2 (95% CI 2.4, 11.0) higher BMD and a 5.4 g (95% CI 1.3, 9.6) higher BMC adjusted for BA of the child. Current weight turned out to mediate these associations. Among mothers who did not smoke, paternal smoking did not show evident associations with childhood bone measures. Also, household smoking practices during childhood were not associated with childhood bone measures.
Conclusions: Our results do not support the hypothesis of foetal smoke exposure affecting childhood bone mass via intrauterine mechanisms. Maternal smoking or related lifestyle factors may affect childhood weight gain rather than skeletal growth.
Disclosure: The authors declared no competing interests. The general design of the Generation R Study was financially supported by the Erasmus Medical Center and Erasmus University, Rotterdam, the Dutch Ministry of Health, Welfare and Sport, and the Netherlands Organization for Health Research and Development (ZonMw). Two coauthors received a grant from ZonMW (VIDI 016.136.361 and VIDI 016.136.367).