Abstract
ObjectiveForthcoming legislative changes will legalize and make cannabis widely available in Canada. We conducted an analysis of Ontario’s birth registry to determine recent trends and correlates of cannabis use in pregnancy.MethodsWe conducted a population-based retrospective cohort study assembled from the Better Outcomes Registry & Network (BORN) Ontario database, covering live births and stillbirths in Ontario between April 2012 and December 2017. Trends in self-reported cannabis use in pregnancy were analyzed according to maternal age and area-level socio-economic status (SES) using log binomial regression analysis.ResultsA total of 10,731 women reported cannabis use in pregnancy. Prevalence increased from 1.2% in 2012 to 1.8% in 2017 (p-trend, < 0.001), equivalent to a relative increase of 61% (relative risk [RR] 1.61, 95% confidence interval [CI] 1.51 to 1.72). The crude prevalence of cannabis use in pregnancy among women aged 15 to 24 years and in the lowest two area-level income quintiles was 6.7%, compared to 0.3% among women aged 35 years and over in the highest three income quintiles (RR 24.59, 95% CI 21.98 to 27.52). A majority (52.0%) of cannabis users were aged 15–24 years and 54.7% of users were in the lowest two income quintiles.ConclusionCannabis use in pregnancy has increased since 2012 in Ontario and was reported in about 2% of pregnancies in 2017. Increases were predominately among women of younger ages and those of lower SES, and these groups account for half of users. Promoting cannabis cessation in pregnancy could lead to improved perinatal and later childhood outcomes and reduce health inequalities.
Highlights
In 2017, the Government of Canada introduced legislation to allow the consumption, sale, and distribution of cannabis for non-medical uses by October 2018 (Government of Canada 2016)
We evaluated recent trends and correlates of cannabis use in pregnancy
A majority (69.7%) were from urban areas with greater than 100,000 inhabitants and 24.8% (n = 182,009) fell into the highest income quintile based on residential postal code. 1.5% (n = 10,731) of women used cannabis in pregnancy and 9.1% used cigarettes at the first prenatal visit (Table 1)
Summary
In 2017, the Government of Canada introduced legislation to allow the consumption, sale, and distribution of cannabis (marijuana) for non-medical uses by October 2018 (Government of Canada 2016). Cannabis is the most widely used illicit drug in Canada, and the prevalence has been increasing in recent years following a period of decline from 2004 to 2011 (Government of Canada 2015). The 2015 Canadian Tobacco, Alcohol and Drugs Survey indicated that the prevalence of past-year cannabis use was 12% of the overall population (3.6 million individuals), but was 21% among young women and men 15 to 19 years of age (Government of Canada 2015). In Canada, legalization may likely increase the availability of cannabis (Pacula et al 2013), decrease the perceptions of harm (Ko et al 2015), and lead to further increases in use, including among pregnant women
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