Prenatal cocaine exposure and age of sexual initiation: direct and indirect effects

Prenatal cocaine exposure (PCE) has been linked to child behavior problems and risky behavior during adolescence such as early substance use. Behavior problems and early substance use are associated with earlier initiation of sexual behavior. The goal of this study was to examine the direct and indirect effects of PCE on sexual initiation in a longitudinal birth cohort, about half of whom were exposed to cocaine in utero.

Women were interviewed twice prenatally, at delivery, and 1, 3, 7, 10, 15, and 21 years postpartum. Offspring (52% female, 54% African American) were assessed at delivery and at each follow-up phase with age-appropriate assessments. At age 21, 225 offspring reported on their substance use and sexual behavior.

First trimester cocaine exposure was a significant predictor of earlier age of first intercourse in a survival analysis, after controlling for race, sociodemographic characteristics, caregiver pre- and postnatal substance use, parental supervision, and child's pubertal timing. However, the association between PCE and age of first sexual intercourse was mediated by adolescent marijuana and alcohol use prior to age 15.

Most of the effect of PCE on age of sexual initiation occurred between the ages of 13-18, when rates of initiation were approximately 10% higher among exposed offspring. This effect was mediated by early adolescent substance use. These results have implications for identification of the exposed offspring at greatest risk of HIV risk behaviors and early, unplanned pregnancy.