The Effect of Prenatal Substance Use and Maternal Parenting on Infant Reactivity and Regulation

Early temperament, particularly regulation and reactivity, is critical to neurodevelopment and can be shaped by early biological and environmental factors. Prenatal substance exposure is one such influencing factor, often associated with lower regulation and heightened reactivity in infants. However, positive parenting may help mitigate these effects. This study examined how prenatal exposure to alcohol, tobacco, and marijuana influences infant temperament at 24 months, and whether maternal warmth at 12- and 24-months moderates or mediates these relationships. Participants were 404 mother-child dyads from a prospective, ethnically diverse urban cohort. Results showed prenatal alcohol and tobacco exposure was directly associated with poorer child regulation and reactivity, while marijuana was not independently linked to these outcomes. Maternal warmth at 12 and 24 months moderated some of the negative effects of prenatal tobacco and marijuana exposure, but not alcohol. These moderating effects varied by child outcome, timing, and frequency of substance use. No evidence was found for maternal warmth mediating any of the associations between prenatal substance use and child outcomes. Findings highlight the differential impact of substance type, timing, and frequency on child outcomes and underscore the importance of early parenting support as a resilience factor.