Co-occurrence of mental illness and substance use among US pregnant individuals, 2012-2021.

Aim: Substance use disorders are increasingly prevalent among pregnant individuals, with evident risks of adverse perinatal outcomes. This study examines substance use (tobacco, alcohol and marijuana) among pregnant individuals with mental illness.

Methods: A national representative sample of pregnant individuals were derived from 2012 to 2021 National Survey of Drug Use and Health data. Associations of past-year mental illness with past-month polysubstance use and each substance use were analyzed by logistic regression models, with complex sampling weights and survey year.

Results: Among 6801 pregnant individuals, 16.4% reported having any mental illness (AMI) in 2012 and 2013, increasing to 23.8% in 2020-2021; and SMI increased from 3.3% to 9.4%. Polysubstance use increased disproportionately among those with severe mental illness (SMI), from 14.0% to 18.6%. Pregnant individuals with greater severity of mental illness had higher odds of polysubstance use (Adjusted Odds Ratio, 95% CI: AMI but no SMI vs. without AMI: 1.59 [1.04, 2.44]; SMI vs. without AMI: 5.48 [2.77, 10.82]).

Conclusions: Pregnant individuals with greater severity of mental illness were more likely to engage in substance use. Evidence-based educational, screening and treatment services, and public policy changes are warranted to mitigate the harmful health outcomes of substance use among US pregnant individuals with mental illness.