The roles of familial transmission and smoking during pregnancy on executive function skills: A sibling-comparison study.

This research examines maternal smoking during pregnancy and risk for poorer executive function in siblings discordant for exposure. Data ( = 173 families) were drawn from the Missouri Mothers and Their Children study, a sample, identified using birth records (years 1998-2005), in which mothers changed smoking behavior between two pregnancies (Child 1 [older sibling]: = 12.99; Child 2 [younger sibling]: = 10.19). A sibling comparison approach was used, providing a robust test for the association between maternal smoking during pregnancy and different aspects of executive function in early-mid adolescence. Results suggested within-family (i.e., causal) associations between maternal smoking during pregnancy and one working memory task (visual working memory) and one response inhibition task (color-word interference), with increased exposure associated with decreased performance. Maternal smoking during pregnancy was not associated with stop-signal reaction time, cognitive flexibility/set-shifting, or auditory working memory. Initial within-family associations between maternal smoking during pregnancy and visual working memory as well as color-word interference were fully attenuated in a model including child and familial covariates. These findings indicate that exposure to maternal smoking during pregnancy may be associated with poorer performance on some, but not all skills assessed; however, familial transmission of risk for low executive function appears more important.