Prenatal exposure to cigarette smoke and childhood externalizing behavioral problems: a propensity score matching approach.

We examined the possibility that the association between maternal smoking during pregnancy and childhood behavioral problems is the result of confounding. Data from the first three waves of the Fragile Families and Child Wellbeing Study were analyzed. We estimated the association between maternal smoking during pregnancy and externalizing problems in three-year olds using a propensity score matching approach. After successfully matching children based on their mother's propensities to smoke during pregnancy, the results indicate that maternal cigarette smoking is related to childhood externalizing behavioral problems, but only among mothers who smoked more than a pack per day while pregnant. At lower levels of exposure, the association between exposure to cigarette smoke in utero and externalizing behavioral problems in childhood can be explained by confounding. The results of this study support prevention efforts intended to reduce prenatal exposure to cigarette smoke, especially by mothers who smoke heavily.