Substance use and the risk for sexual intercourse with and without a history of teenage pregnancy among adolescent females.

OBJECTIVE: The present study examined the associations between initiation and intensity of substance use and with sexual experience with and without a history of teenage pregnancy.
METHOD: Participants were high school females (weighted n = 3,451) who participated in the 1999-2003 Youth Risk Behavior Surveillance System, a cross-sectional, nationally representative survey. Multinomial multivariable logistic regression was used to assess the likelihood of being sexually experienced (but never pregnant) and teenage pregnancy (reference group: never had sexual intercourse) as a function of age at substance use initiation (i.e., age 12 or younger, 13-14 years of age, and age 15 or older) and intensity of substance use (i.e., nonuser, experimental/ new or nondaily, nonexperimental/daily user) for alcohol, cigarettes, and marijuana, while controlling for race/ethnicity, metropolitan location, symptoms of depression, and illegal drug availability at school.
RESULTS: A major finding of our study is that substance use behaviors across each substance (alcohol, cigarettes, and marijuana) independently contributed to an increased risk in sexual intercourse experience with and without a history of teenage pregnancy (vs. nonsexually experienced females). A dose-response relationship was also observed between an increased likelihood of a teenage pregnancy and marijuana behaviors. Furthermore, the risk for teenage pregnancy was compounded for daily cigarette smokers who initiated use at age 12 or younger.
CONCLUSIONS: Screening substance use behaviors can help to identify girls who may benefit from pregnancy prevention strategies. Targeting cigarette and marijuana behaviors as early as age 12 or younger may provide an added benefit. Prevention strategies should also consider the role of race above and beyond substance use behaviors.