Background: With expanding recreational cannabis legalisation, pregnant women and their offspring are at risk of potentially harmful consequences.
Objectives: To assess the prevalence of recreational cannabis use among pregnant women, health outcomes associated with prenatal recreational cannabis use, and the potential impact of recreational cannabis legalisation on this population.
Search strategy: Five databases and the grey literature were systematically searched (2000-2019).
Selection criteria: Human studies published in English or French reporting on the prevalence of prenatal recreational cannabis use in high-income countries.
Data collection and analysis: Data on study characteristics, prenatal substance use, and health outcomes were extracted and qualitatively synthesised.
Main results: Forty-one publications met our inclusion criteria. The overall prevalence of prenatal cannabis use varied substantially (min-max: 0.24-22.6%), with the greatest use in the first trimester. In the three studies with temporal data available, rates of prenatal cannabis use increased across years. Only 7/41 and 5/41 studies provided information on gestational age of exposure and frequency of use, respectively. The concomitant use of alcohol, illicit drugs, and tobacco was higher among cannabis users than nonusers. Prenatal cannabis use was associated with select neonatal, but not maternal, health outcomes. There were insufficient data to compare prenatal cannabis use between the pre- and post-legalisation periods.
Conclusion: Cannabis use among pregnant women is prevalent and may be associated with adverse neonatal outcomes. Future studies should assess the gestational age and frequency of cannabis exposure, and usage patterns prior to and following legalisation.
Tweetable abstract: Women who consume cannabis during pregnancy could risk predisposing their newborns to poor birth outcomes.
Keywords: Cannabis; maternal health; neonatal health; pregnancy; scoping review.
© 2019 Royal College of Obstetricians and Gynaecologists.