Wei Bao, Karin B Michels, Deirdre K Tobias, Shanshan Li, Jorge E Chavarro, Audrey J Gaskins, Allan A Vaag, Frank B Hu, Cuilin Zhang

Fetal exposure to parental smoking may have long-term impact on the development of disease in adulthood. We examined the association of parental smoking during pregnancy with risk of gestational diabetes mellitus (GDM) in the daughter. We included 15 665 singleton pregnancies from 10 152 women in the Nurses' Health Study II cohort whose mothers participated in the Nurses' Mothers' Cohort Study. Data on maternal and paternal smoking during pregnancy and associated covariates were recalled by the mothers. GDM diagnosis was self-reported by the daughters and was validated by medical record review in a previous study. We used log-binomial models with generalized estimating equations to estimate relative risks (RRs) and 95% confidence intervals (CIs). We observed a positive association between maternal heavy smoking during pregnancy and risk of GDM in the daughter. The multivariable-adjusted RRs (95% CIs) of GDM among women whose mothers did not smoke during pregnancy, continued smoking 1-14, 15-24, and ≥25 cigarettes/day were 1.00 (reference), 1.05 (0.81-1.35), 1.27 (0.95-1.70) and 1.98 (1.18-3.30), respectively (P for trend = 0.01). Further adjustment for the women's perinatal variables, adult-life characteristics and body mass index during various periods of life modestly attenuated the association. No association was observed between paternal smoking during the pregnancy period and risk of GDM in the daughter. Maternal heavy smoking (≥25 cigarettes/day) during pregnancy was associated with higher risk of gestational diabetes in the daughter. Further studies are warranted to confirm our findings and to elucidate the underlying mechanisms.