The association of preconception and prenatal cannabis and tobacco exposure with autism symptoms in offspring: A population-based longitudinal study

Prenatal cannabis and tobacco exposure is associated with attention and behavior problems in children, while associations with autism symptoms remain unclear. We prospectively examined whether parental cannabis and tobacco use during pregnancy were associated with childhood autism symptoms. Information on parental cannabis and tobacco use was assessed using questionnaires, and maternal cannabis metabolites were detected via urinalysis. We measured autistic symptoms using two mother-reported instruments: Child Behavior Checklist (CBCL) at ages 1.5, 3, and 6; and Social Responsiveness Scale (SRS) at 6 years (n = 4380). Linear mixed models were used to examine the association between parental cannabis and tobacco use and CBCL autism symptoms across childhood. Linear regression was used for SRS autism symptoms. Maternal cannabis use before, but not during, pregnancy was associated with higher CBCL autism symptoms across childhood (β: 0.33, 95 % CI: 0.02, 0.63). Paternal cannabis use was linked to higher CBCL autism symptoms across childhood (β: 0.27, 95 % CI: 0.05, 0.50), explained by maternal psychopathology; no association was found with SRS autism symptoms. Excluding cannabis users, children whose mothers used tobacco throughout pregnancy had more SRS autism symptoms (β: 0.03, 95 % CI: 0.003, 0.05), not CBCL; no association was found with paternal tobacco use. Our results suggest that maternal and paternal cannabis use is not associated with offspring autism symptoms, although preconception use is associated with autism symptoms across childhood. In contrast, maternal continued tobacco use during pregnancy was associated with autism symptoms, but not paternal use, suggesting possible intrauterine programming rather than family-based factors.