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.

Background Pregnant smokers are often prescribed counselling as part of multicomponent cessation interventions. However, the isolated effect of counselling in this population remains unclear, and individual randomised controlled trials (RCTs) are inconclusive.Objective To conduct a meta-analysis of RCTs examining counselling in pregnant smokers.Search strategy We searched the CDC Tobacco Information and Prevention, Cochrane Library, EMBASE, Medline and PsycINFO databases for RCTs evaluating smoking cessation counselling.Selection criteria We included RCTs conducted in pregnant women in which the effect of counselling could be isolated and those that reported biochemically validated abstinence at 6 or 12 months after the target quit date.Data collection and analysis Overall estimates were derived using random effects meta-analysis models.Main results Our search identified eight RCTs (n = 3290 women), all of which examined abstinence at 6 months. The proportion of women that remained abstinent at the end of follow up was modest, ranging from 4 to 24% among those randomised to counselling and from 2 to 21% among control women. The absolute difference in abstinence reached a maximum of only 4%. Summary estimates are inconclusive because of wide confidence intervals, albeit with little evidence to suggest that counselling is efficacious at promoting abstinence (odds ratio 1.08, 95% confidence interval 0.84-1.40). There was no evidence to suggest that efficacy differed by counselling type.Conclusions Available data from RCTs examining the isolated effect of smoking cessation counselling in pregnant women are limited but sufficient to rule out large treatment effects. Future RCTs should examine pharmacological therapies in this population.

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