Pre- and postnatal tobacco and cannabis exposure and child behavior problems: Bidirectional associations, joint effects, and sex differences.

Aims: We examined prospective associations between pre-and-postnatal tobacco and cannabis exposure on child behavior problems from 2 to 3 years of child age, sex differences in these associations, and bidirectional associations between maternal postnatal substance use and child behavior problems across time.

Methods: The sample consisted of 247 primarily young, unmarried, low-income, minority mothers and their children (97 prenatally exposed to tobacco and cannabis, 81 exposed to tobacco only, and 69 non-exposed). Mothers were assessed during each trimester of pregnancy, at 2, 9, 16 months, 2 and 3 years of child age.

Results: Bivariate results indicated significant differences mainly for girls. Girls in the prenatal tobacco exposure group had higher internalizing problems compared to the other two groups, and higher attention and sleep problems at 3 years compared to the control group. Higher number of cigarettes per day during pregnancy was significantly associated with higher anxiety/depression and higher attention problems at 3 years, and the associations were stronger for girls compared to boys. In model testing controlling for prenatal exposure, results indicated bidirectional associations between behavior problems at 2 years and maternal postnatal cannabis use, such that higher cannabis use across the infant toddler period predicted higher behavior problems at 2 years, which in turn predicted higher cannabis use a year later.

Conclusions: Results add to the literature on joint effects of tobacco and cannabis, highlight the importance of considering bidirectional associations between maternal substance use and child behavior problems, and indicate generally stronger prenatal tobacco exposure effects for girls.