FRIDAY, Nov. 6 (HealthDay News) -- Maternal smoking is associated with disruptive behavior in 3-year-olds, but the effect varies by gender, the extent to which the mother smoked, and the interaction with other co-occurring conditions, according to a study published online Nov. 3 in the Journal of Epidemiology and Community Health.

Jayne Hutchinson, of the University of York in the United Kingdom, and colleagues analyzed data from the U.K. Millennium Cohort Study on more than 13,000 3-year-old boys and girls, which provided self-reported information on smoking in pregnancy and maternal reports of childhood behavior.

Compared with having a non-smoking mother, having a mother who persistently smoked during pregnancy was associated with significant risk of problems with hyperactivity-inattention and conduct for boys, but the effect of smoking varied according to whether or not the children had co-occurring problems, and the extent to which the mother smoked, the researchers found. For girls, having a smoking mother was found to be associated with conduct problems.

"Smoking during pregnancy may have direct effects on the development of behavior problems, most plausibly via adverse teratological effects on the fetal development of brain structure and functioning, which is well-characterized in animal models," the authors write. "Rather than genes, exposure or environment being sole causes, the etiology of disruptive behavior disorders most likely involves gene-exposure-environment interactions."

Abstract
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