Substance use patterns among individuals who consume alcohol during pregnancy: Results from a US multi-site study

Introduction: Prenatal alcohol exposure (PAE) is common and associated with adverse outcomes, yet the impact of concurrent substance use remains poorly understood. Using HEALthy Brain and Child Development (HBCD) data (n = 1426), we described alcohol use patterns—with and without other substances—and examined factors associated with alcohol use in pregnancy. Methods: Data were obtained from the HBCD Study public release 1.0, a 27-site longitudinal cohort examining normative development and the effects of four primary substances (alcohol, cannabis, tobacco, and opioids). More-than-minimal PAE was assessed by self-report and ethanol biomarkers. Participants were classified into 3 study groups: a) Alcohol-Only; b) Alcohol-Plus (alcohol with ≥1 other substance); and c) Comparison (alcohol use below the threshold and negative ethanol biomarkers). Correlates of alcohol use were assessed via polychotomous logistic regression contrasting two alcohol-use categories relative to a common reference group. Results: More-than-minimal alcohol use occurred in 12.7% of participants, with 37% of these also using other substances. The most common polysubstance use pattern was a combination of alcohol, cannabis, and/or nicotine, which occurred, in different combinations, among 28% of participants. Maternal mental health disorders were positively associated with both Alcohol-Only and Alcohol–Plus use. Higher socioeconomic status (SES) was associated with Alcohol-Only use, whereas lower SES was associated with Alcohol–Plus use. Conclusions: Over one-third of pregnant individuals who used alcohol also used at least one additional substance. Observed associations with maternal mental health and SES highlight opportunities for targeted policy, enhanced screening, and tailored interventions to support maternal and child health.