Few, if any, studies have systematically examined the relationship between substance use and teen pregnancy using population-based samples. We aim to provide a comprehensive examination of substance use among pregnant adolescents in the United States.Employing data from the National Survey on Drug Use and Health between 2002 and 2012 (n=97,850), we examine the prevalence of the past 12-month and the past 30-day substance use and substance use disorders among pregnant and non-pregnant adolescents (ages 12-17). We also examine psychosocial and pregnancy-related correlates of current substance use among the subsample of pregnant adolescents (n=810).Pregnant teens were significantly more likely to have experimented with a variety of substances and meet criteria for alcohol (AOR=1.65, 95% CI=1.26-2.17), cannabis (AOR=2.29, 95% CI=1.72-3.04), and other illicit drug use disorders (AOR=2.84, 95% CI=1.92-4.19). Pregnant early adolescents (ages 12-14; AOR=4.34, 95% CI=2.28-8.26) were significantly more likely and pregnant late adolescents (ages 15-17; AOR=0.71, 95% CI=0.56-0.90) significantly less likely than their non-pregnant counterparts to be current substance users.Study findings point not only to a relationship between pregnancy and prior substance use, but also suggest that substance use continues for many teens during pregnancy. We found that substance use is particularly problematic among early adolescents and that the prevalence of substance use attenuates dramatically as youth progress from the first to the second and third trimesters of pregnancy.