Associations Between Infant Developmental Delays and Secondhand Smoke Exposure Modified by Maternal Prepregnancy Overweight and Obesity Status.

The study results suggested the association between maternal secondhand smoke exposure during pregnancy and infancy and delayed fine motor and language-related milestone achievement at 18 months in multivariable, propensity score weighting, and matching populations. The results of positive effect modifications for maternal prepregnancy overweight and obesity status suggested the importance of concurrent interventions on smoke-free environment and maternal health during pregnancy.