Objective: To investigate the association between maternal smoking during pregnancy and hyperactivity in 8-year-old children.
Method: The study population consisted of children from the Northern Finland 1985/86 Birth Cohort. At 8-year follow-up 9,357 children were alive. Mothers provided information both during pregnancy and at age 8. Teachers assessed children's behavior by the Children's Behavior Questionnaire (Rutter B2). Unadjusted analyses and stratification were used to study associations and confounding variables. A multivariate logistic regression model was fitted to assess the independent association between smoking and outcome.
Results: Maternal smoking was associated with hyperactivity even after adjustment for sex, family structure, socioeconomic status, maternal age, and maternal alcohol use (odds ratio 1.30; 1.08-1.58). The association was particularly notable among children of young mothers with low social standing. A positive dose-response relationship was seen between maternal smoking and hyperactivity.
Conclusion: This study, the largest population-based prospective follow-up on fetal nicotine exposure and later behavioral disorders, confirms earlier descriptions of the link between maternal smoking during gestation and childhood hyperactivity. Discontinuation or decreased use of cigarettes during pregnancy might improve behavioral outcome of children.