Marijuana and tobacco co-use among a nationally representative sample of US pregnant and non-pregnant women: 2005-2014 National Survey on Drug Use and Health findings

Background: Marijuana and tobacco are the most commonly used illicit and licit drugs during pregnancy. This study aimed to examine a nationally representative sample of US pregnant women and to: (1) determine the prevalence of past month marijuana and tobacco co-use, (2) identify characteristics that distinguish marijuana and tobacco co-users from users of marijuana only, tobacco only, or neither, and (3) compare characteristics that differ between pregnant and non-pregnant co-users of marijuana and tobacco. Methods: Data were obtained from 497,218 US women (8721 pregnant) ages 12-49 who participated in the 2005-2014 National Survey on Drug Use and Health. Prevalence and demographic and substance use characteristics were compared across groups using weighted estimates and chi-squared tests. Multinomial logistic regression identified demographic and substance use correlates of co-use. Results: Co-use among pregnant and non-pregnant women was significantly more prevalent than marijuana-only use but was less common than tobacco-only use. In unadjusted frequencies, pregnant co-users significantly differed from non-pregnant co-users across several domains. Among pregnant women, multivariate correlates of co-use of tobacco and marijuana vs. tobacco-only use were ages 12-17, non-Hispanic black race, Hispanic ethnicity, and past month polytobacco, any alcohol, and other drug use (all adjusted odds ratios 2.0). Conclusions: In this first examination of the prevalence and correlates of co-use of marijuana and tobacco among a nationally representative group of pregnant women, pregnant co-users were more likely to report other high risk behaviors compared with non-pregnant co-users and users of a single substance, suggesting disparities worthy of further investigation.