Developmental Cascades From Prenatal Tobacco, Tobacco-cannabis Co-exposure to Early school-age externalizing Problems.

Prenatal tobacco (PTE) and tobacco cannabis co-exposure (PTCE) are associated with higher risk for child externalizing problems. However, developmental mechanisms for the PTE association and the PTCE related associations are poorly understood. We tested multiple mechanistic developmental pathways (emotion regulation, temperament, maternal negative mood, and continued postnatal tobacco exposure) from PTE and PTCE to early school age externalizing problems. The sample consisted of 293 diverse (48% Black, 27% White, 14% Hispanic, and 11% other or mixed race; 64.8% WIC recipients) mother-child dyads grouped as: PTE (n = 89; 62.92% male), PTCE (n = 105; 47.62% male), and demographically similar non-substance-exposed mother-child dyads (n = 99; 43.43% male). Substance exposure was assessed using multiple methods, maternal negative mood using self-report, emotion regulation using physiological methods in infancy and observations in toddlerhood, temperament with maternal-report in infancy and toddlerhood, and child postnatal tobacco exposure using salivary cotinine across time points. Externalizing problems were assessed in toddlerhood and early school age using maternal-report and at school age using teacher-report. PTCE was associated with an emotion regulation pathway and PTE was associated with a combined maternal negative mood and temperament pathway to externalizing problems. Although both PTE and PTCE were associated with heightened externalizing problems at early school age, PTE and PTCE were significantly related to unique underlying pathways to externalizing problems. Therefore, targets for prevention efforts for children with PTE and PTCE may need to vary based on the type of exposure a child experiences.