Prenatal Smoke Exposure and ADHD: Advancing the Field.

A robust literature indicates a link between maternal smoking during pregnancy and subsequent diagnosis of attention-deficit/hyperactivity disorder (ADHD) in children. However, questions have been raised regarding whether this association is causal and attributable to intrauterine effects or due to other unmeasured factors. Gustavson and colleagues 1 tested this question using a large prospective birth cohort; the findings from their thorough analyses are presented in their paper, “Smoking in pregnancy and child ADHD” published in the current issue of Pediatrics. The results showed that maternal smoking during pregnancy was not more strongly associated with childhood ADHD than maternal smoking during previous pregnancies, paternal smoking, or grandmothers’ smoking while pregnant with the mother. In addition, the analyses looking at sibling controls also did not suggest that children were more likely to exhibit ADHD symptoms when mothers smoked during pregnancy compared with siblings who did not experience prenatal smoke exposure. This well-designed study replicated other findings 2 that indicate maternal smoking may not be a causal risk factor and that the association may be better explained by other genetic or environmental mechanisms.