Maternal Prenatal Cannabis Use and Major Structural Birth Defects.

Objective: We evaluated associations between prenatal cannabis use and major structural birth defects of the child.

Methods: This population-based retrospective cohort study comprised singleton births (January 2011-July 2020) universally screened for substance use at entrance to prenatal care. Prenatal cannabis use was defined as self-reported use or a positive toxicology test during pregnancy. Electronic health record and birth certificate data were used to identify 38 specific major structural birth defects within 8 organ systems (i.e., central nervous, eye, ear, cardiac, orofacial/respiratory, gastrointestinal, genitourinary/renal, and musculoskeletal). Modified Poisson regression models were conducted adjusting for propensity scores.

Results: Of 363,952 infants, 22,494(6.2%) were exposed to maternal prenatal cannabis use, and 6094 infants (2.17%) had a major structural birth defect. Maternal prenatal cannabis use was associated with gastroschisis in the unadjusted (RR = 2.00, 95% CI: 1.25-3.19) and other non-cannabis prenatal substance use (aRR = 1.68; 95% CI: 1.04-2.71) adjusted models, but not in the models adjusted for maternal age or the propensity score. Maternal prenatal cannabis use was associated with omphalocele in the unadjusted model (RR = 3.04; 95% CI: 1.42-6.48), maternal age-adjusted model (aRR = 3.54; 95% CI: 1.68-7.48), other prenatal substance use-adjusted model (aRR = 3.31; 95% CI: 1.50-7.31), and propensity score adjusted model (aRR: 2.92, 95% CI: 1.26-6.77). Cases of gastroschisis and omphalocele were rare: n = 172 (0.05%) and n = 48 (0.01%), respectively. No associations emerged between maternal prenatal cannabis use and any other birth defects. Findings were replicated when cannabis was defined by toxicology testing only.

Conclusions: Maternal prenatal cannabis use was associated with an increased risk for gastroschisis and omphalocele. Clinicians should provide counseling in a supportive manner to pregnant individuals about the potential harms associated with prenatal cannabis use.