The effects of illicit drug use during pregnancy and parental hostility on problem behaviors in school-aged children over and above genetic influences.

Previous work has examined the impact of prenatal illicit drug use (PDU) on children’s problem behaviors. However, many PDU-related risk factors, including genetic and rearing environmental risks, can also influence offspring’s problem behaviors, thus confounding PDU, genetic, and rearing environmental influences. This study aimed to (a) identify effects of PDU on school-aged children’s problem behaviors, including both externalizing and internalizing behaviors at Age 7, after controlling genetic and specific rearing environmental (e.g., maternal and paternal hostility at Ages 4.5 and 6) influences and (b) examine interaction effects between PDU and maternal and paternal hostility in predicting children’s problem behaviors at Age 7. We used a parent–offspring adoption design to partition genetic and prenatal effects from postnatal rearing environmental influences. Participants were 561 children adopted at birth (42% female; 56% White, 19% multiracial, 13% Black/African American, 11% Latine, and 1% other), their adoptive parents, and their birth parents. Results indicate that PDU did not show a direct impact on Age 7 problem behaviors before or after controlling genetic risks and adoptive mother’s and father’s hostility. However, we found significant interactions between adoptive father’s hostility and PDU when predicting children’s problem behaviors, such that higher paternal hostility was associated with higher externalizing and internalizing behaviors for children whose birth mothers were non-use or rare use of illicit drugs during pregnancy. The results suggest that different from non- or rare drug-exposed children, higher levels of PDU may override the effects of paternal hostility, but not maternal hostility, on problem behaviors at Age 7. The results suggest that school-aged children with prenatal drug exposure raised in genetically unrelated adoptive families may not be different from unexposed children with respect to problem behaviors at Age 7. However, children with non- or rare-drug exposure were more sensitive to the effect of paternal hostility on problem behaviors at Age 7, compared to children who had higher levels of prenatal drug exposure. Moreover, the findings indicate that maternal hostility may have pervasive impacts on children’s problem behaviors, regardless of children’s predisposition (e.g., exposure to prenatal illicit drugs).