Contemporary social context and patterns of prenatal cannabis use in Canada following legalization: a secondary analysis of prospective cohort data.

BackgroundThe epidemiology of prenatal cannabis use in Canada following legalization remains unknown despite increasing evidence for associated health risks. Our study aimed to identify current risk factors for, and patterns of, prenatal cannabis use and second-hand cannabis exposure in Alberta. MethodsWe conducted a secondary analysis of prospective data from a 2019 study in Calgary AB, of 153 pregnant (<28 weeks gestation at enrollment), English-speaking Alberta residents. We conducted descriptive analyses of prenatal cannabis use patterns (timing, frequency, dose, modes and reasons for use) and logistic regression to identify risk factors for direct use and second-hand exposure. ResultsOdds of prenatal cannabis use were significantly higher among those who did not own their home (Odds Ratio (OR) 3.1; 95% CI:1.6-9.6), smoked tobacco prenatally (OR 3.3,95% CI:1.2-9.3) and used illicit substances in the past (OR 3.2; 95% CI:1.7-9.9), and lower for those consuming alcohol prenatally (OR 0.3, 0.12-0.89). Among the 90 (58%) participants who used cannabis prenatally, the majority used for medicinal reasons (96%), at least daily (67%), by smoking (88%), in all trimesters of pregnancy (66%). Although reported dose-per-use was commonly low, cumulative doses over pregnancy were high. InterpretationOur study finds marked differences in prenatal cannabis use risk factors, and patterns of more frequent use sustained throughout pregnancy with perceived medicinal indications than pre-legalization studies. Prenatal care providers should include cannabis explicitly in medication counselling. Further prospective studies are needed as the impacts of prenatal cannabis on maternal and infant health in Canada may currently be underestimated.