Patterns of substance use during pregnancy are differentially associated with maternal mental health across the perinatal period

Background: Substance use during pregnancy can substantially increase risk for postpartum depression and anxiety symptoms, which can have lasting effects on family functioning and child development. However, substance use is often conceptualized as a binary exposure, limiting our understanding of whether specific patterns of use are associated with maternal mental health in the perinatal period. Here, we examined longitudinal patterns of prenatal alcohol use and smoking in relation to maternal depressive and anxiety symptoms across pregnancy and the first two years postpartum. Methods: We analyzed prospective data from the Avon Longitudinal Study of Parents and Children (ALSPAC), a population-based cohort from the UK. Alcohol and cigarette use were assessed across all three trimesters and modeled as longitudinal patterns (abstained, persistent, intermittent, discontinued). Maternal depressive and anxiety symptoms were measured from the second trimester through 21 months postpartum using the Crown-Crisp Experiential Index. Results: Persistent alcohol use was associated with higher depressive and anxiety symptoms and slower symptom declines over time, while women with intermittent or discontinued use had symptom profiles similar to abstainers. By contrast, persistent, intermittent, and quitting smoking patterns were associated with higher symptom levels overall, with persistent smoking additionally associated with steeper declines in symptoms over time. Conclusion: Our findings highlight the importance of considering the persistence and cessation of substance use during pregnancy in the context of maternal mental health, pointing to patterns of persistent substance use as a potential target to inform screening and early intervention for women at higher risk for perinatal psychological distress.