The goal of this study was to examine the effects of early and adverse experiences with sex and alcohol on adolescent drinking the year before and during pregnancy. Pregnant adolescents, recruited at an outpatient prenatal clinic, were interviewed about their substance use. A subsample was asked about their first sexual experiences. Associations among early experiences with alcohol and sex and drinking before and during pregnancy were examined. Early age at first alcoholic drink predicted problem alcohol use before pregnancy and drinking during pregnancy. Coercive first coitus was not associated with alcohol use, but drinking during first coitus predicted problem alcohol use before pregnancy as well as drinking during the first trimester of pregnancy. In sum, early use of alcohol and use of alcohol during first coitus may be risk factors for problematic alcohol use before pregnancy and during pregnancy among childbearing teenagers. Implications for the health of adolescent mothers and their offspring are discussed.