Maternal and paternal cannabis use during pregnancy and the risk of psychotic-like experiences in the offspring.

Cannabis use continues to increase among pregnant women. Gestational cannabis exposure has been associated with various adverse outcomes. However, it remains unclear whether cannabis use during pregnancy increases the risk for offspring psychotic-like experiences. In this prospective cohort, we examined the relationship between parental cannabis use during pregnancy and offspring psychotic-like experiences. Comparisons were made between maternal and paternal cannabis use during pregnancy to investigate causal influences of intra-uterine cannabis exposure during foetal neurodevelopmental. This study was embedded in the Generation R birth cohort and included N = 3692 participants. Maternal cannabis exposure was determined using self-reports and cannabis metabolite levels from urine. Paternal cannabis use during pregnancy was obtained by maternal report. Maternal cannabis use increased the risk of psychotic-like experiences in the offspring (ORadjusted = 1.38, 95% CI 1.03-1.85). Estimates were comparable for maternal cannabis use exclusively before pregnancy versus continued cannabis use during pregnancy. Paternal cannabis use was similarly associated with offspring psychotic-like experiences (ORadjusted = 1.44, 95% CI 1.14-1.82). We demonstrated that both maternal and paternal cannabis use were associated with more offspring psychotic-like experiences at age ten years. This may suggest that common aetiologies, rather than solely causal intra-uterine mechanisms, underlie the association between parental cannabis use and offspring psychotic-like experiences. These common backgrounds most likely reflect genetic vulnerabilities and shared familial mechanisms, shedding a potential new light on the debated causal path from cannabis use to psychotic-like phenomena. Our findings indicate that diagnostic screening and preventative measures need to be adapted for young people at risk for severe mental illness.