- Prenatal cannabis use is prevalent, but declines through pregnancy.
- Paucity of data on quantification of cannabis exposure by gestational age, frequency, recreational prenatal cannabis use/legalization.
Why this matters
- In August 2019, the US Surgeon General issued a national warning against cannabis use during pregnancy and lactation, citing potential effects on the developing brain.
- Supporting data were limited; metadata provide greater context with larger overall study/participant numbers.
- Discuss potential harms of cannabis, other substances with pregnant patients.
- 41 studies.
- Prenatal cannabis use prevalence: 0.24% to 22.6%; especially ages
- Cannabis use increased during the first trimester (n=1 study): from 5.7% to 12.1%, 2002-2003 to 2016-2017, respectively (difference, 6.4%; 95% CI, 2.6%-10.3%); overall data demonstrated consistent declines in second, third trimesters.
- Concurrent alcohol in 7.6%-64.6% of cannabis users; concurrent illicit drug and tobacco use in 0.5%-61.5% and 27.4%-77.3%, respectively.
- Neonatal outcomes:
- Low birth weight (n=3/7): aOR, 1.5 (95% CI, 1.1-2.1) to 2.72 (95% CI, 1.67-4.43).
- Increased ICU admissions (n=4/6): adjusted relative risk (aRR), 1.40 (95% CI, 1.36-1.44) to aOR, 2.0 (95% CI, 1.7-2.5).
- Preterm birth (n=3/9): aRR, 1.41 (95% CI, 1.36-1.47) to aOR, 2.2 (95% CI, 1.9-2.5).
- Small size (n=5/10): aOR, 1.30 (95% CI, 1.03-1.62) to 2.2 (95% CI, 1.8-2.7).
- Systematic meta-review of recreational prenatal cannabis use, health outcomes in high-income countries, 2000-2019.
- Funding: Canadian Institutes of Health Research.
- Limited generalizability.
- Select neonatal, maternal outcomes.
- Observational, residual confounding.