A MAJOR updated meta-analysis has found that cannabis use during pregnancy is associated with significantly increased risks of adverse neonatal outcomes, strengthening the evidence base for clinical counselling and public health guidance.
Researchers conducted a living systematic review and meta-analysis, updating previous findings with data from studies published between November 2021 and April 2024. The team systematically searched MEDLINE, CINAHL, PsycInfo, Global Health, and the Cochrane Database, selecting cohort and case-control studies that compared pregnancies with and without prenatal cannabis exposure. Studies were required to adjust for key confounders, including tobacco co-use. Data were extracted by two independent reviewers and analysed using random-effects models to calculate adjusted odds ratios (OR) for outcomes including preterm birth, small for gestational age (SGA), low birth weight (LBW), and perinatal mortality.
In total, 51 studies involving over 21 million pregnancies were included, making this the most comprehensive analysis to date. Cannabis use during pregnancy was associated with 75% higher odds of LBW (OR 1.75; 95% CI 1.41–2.18), 52% higher odds of preterm birth (OR 1.52; 95% CI 1.26–1.83), and 57% higher odds of SGA (OR 1.57; 95% CI 1.36–1.81). Although the evidence linking cannabis use to perinatal mortality remained of low certainty, the odds were also increased (OR 1.29; 95% CI 1.07–1.55). Notably, these associations persisted even after adjusting for tobacco use, and the certainty of evidence for several outcomes improved from low to moderate compared with the prior review.
These findings reinforce concerns about prenatal cannabis exposure and should prompt clinicians to explicitly address its risks during antenatal care. With use on the rise and perceptions of safety often underestimated, targeted education and policy interventions are urgently needed.
Reference
Lo JO et al. Prenatal cannabis use and neonatal outcomes: a systematic review and meta-analysis. JAMA Pediatr. 2025; DOI:10.1001/jamapediatrics.2025.0689.
