Changes in prenatal cannabis‐related diagnosed disorders after the Cannabis Act and the COVID‐19 pandemic in Quebec, Canada

Background and aims Public health concerns regarding pregnant women’s health after the enactment of the Cannabis Act in Canada (CAC) (a law that allowed non‐medical cannabis use), and the potential impact of the COVID‐19 pandemic, call for a contemporary assessment of these two events. Our study measured associations between the CAC, the COVID‐19 pandemic and the monthly prevalence rates of cannabis‐, all drug‐ and alcohol‐related diagnosed disorders among pregnant women in the province of Quebec. Design, setting and participants This was a quasi‐experimental design applying an interrupted time‐series methodology in the province of Quebec, Canada. The participants were pregnant women aged 15–49 years, between January 2010 and July 2022. Measurements Administrative health data from the Québec Integrated Chronic Disease Surveillance System were used to classify pregnant women according to cannabis‐, all drug (excluding cannabis)‐ and alcohol‐related disorders. The CAC (October 2018) and the COVID‐19 pandemic (April 2020) were evaluated as (1) slope changes and (2) level changes. Cannabis‐, all drug (excluding cannabis)‐ and alcohol‐related disorders were measured by total monthly age‐standardized monthly prevalence rate of each disorder for pregnant women aged 15–49 years. Findings Before the CAC, the prevalence rate of cannabis‐related diagnosed disorders significantly increased each month by 0.5% [95% confidence interval (CI) = 0.3–0.6] in the pregnant population. After the CAC, there were significant increases of 24% (95% CI = 1–53) of cannabis‐related diagnosed disorders. No significant changes were observed for all drug (excluding cannabis)‐ and alcohol‐related diagnosed disorders associated with the CAC. A non‐significant decrease of 20% (95% CI = −38 to 3) was observed during the COVID‐19 pandemic in alcohol‐related disorders. Conclusions The monthly incidence rates of diagnosed cannabis‐related disorders in pregnant women in Quebec increased significantly following the enactment of the Cannabis Act in Canada. Diagnoses of all drug (excluding cannabis)‐ and alcohol‐related disorders remained relatively stable.