Marijuana use and sexually transmitted infections in young women who were teenage mothers.

PURPOSE: Teenage pregnancy and marijuana use are associated with higher risk of contracting sexually transmitted infections (STIs). In this study, we examined the role of early and current marijuana use as it related to STI risk in a sample of young women who were pregnant teenagers, using a variety of statistical models.
METHODS: We recruited 279 pregnant adolescents, ages 12-18, from an urban prenatal clinic as part of a study that was developed to evaluate the long-term effects of prenatal substance exposure. Six years later, they were asked about their substance use and sexual history. The association of early and late marijuana use to lifetime sexual partners and STIs was examined, and then structural equation modeling (SEM) was used to illustrate the associations among marijuana use, number of sexual partners, and STIs.
RESULTS: Bivariate analyses revealed a dose-response effect of early and current marijuana use on STIs in young adulthood. Early and current marijuana use also predicted a higher number of lifetime sexual partners. However, the effect of early marijuana use on STIs was mediated by lifetime number of sexual partners in the SEM, whereas African-American race, more externalizing problems, and a greater number of sexual partners were directly related to more STIs.
CONCLUSIONS: Adolescent pregnancy, early marijuana use, mental health problems, and African-American race were significant risk factors for STIs in young adult women who had become mothers during adolescence. Pregnant teenage girls should be screened for early drug use and mental health problems, because they may benefit the most from the implementation of STI screening and skill-based prevention programs.