Cannabis use in Pregnancy Copy
Cannabis use in pregnancy and neonatal outcomes: A systematic review and meta-analysis
- In the US, cannabis is the most commonly used illicit drug among women of childbearing age and during pregnancy.
- Approximately half of pregnant individuals who use cannabis continue to use throughout pregnancy, particularly in the first trimester.
- At present, the US Surgeon General and American College of Obstetricians and Gynecologists advise pregnant and lactating individuals to abstain from using cannabis due to concern over detrimental fetal outcomes.
- Prior reviews have been limited by lack of adjustment for important confounding factors (e.g., prenatal tobacco use) and inclusion of studies mostly published before the recent legalization of cannabis by many states.
- This review provides a contemporary understanding of the association between prenatal cannabis exposure and fetal and neonatal outcomes after accounting for tobacco use.
Living systematic review
- CINAHL (EBSCOHost)
- EBM Reviews Cochrane Database of Systematic Reviews (Ovid)
- Global Health (Ovid)
- MEDLINE (Ovid)
- PsycInfo (Ovid)
Screening: Cohort or case-control studies assessing the effects of prenatal cannabis use on risk of preterm birth (less than 37 weeks of gestation; PTB), low birth weight (less than 2,500 grams; LBW), small-for-gestational-age (weight less than the 10th percentile given sex and gestational age; SGA) and perinatal mortality.
Risk of Bias (RoB): Newcastle-Ottawa tool for cohort studies and case-control studies
GRADE: Overall certainty of evidence (CoE) for each outcome using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach
Meta-Analysis: Pairwise meta-analyses using adjusted and unadjusted data.
Updates: Search to be updated every 6 months with new reports as needed
- We identified 53 eligible studies. Of these, 52 were cohort studies and 1 was a case-control study. In general, we rated these studies as low to moderate risk of bias:
- The relationship between cannabis use in pregnancy and birthweight is unclear (n = 31 studies; low CoE)
- Following statistical adjustment, we observed increased odds of PTB (n = 41 studies; low CoE) and SGA (n = 21 studies; low CoE) in infants of individuals who used cannabis in pregnancy
- After adjustment, the odds of perinatal mortality were increased with cannabis use in pregnancy, but the CoE was very low (n = 17 studies)
Summary of Findings (GRADE)
|Certainty of the Evidence||Relationship||Rationale for CoE Rating|
N = 282,699
|Unclear relationship between cannabis use in pregnancy and birthweight||Downgraded 1 level each for RoB and inconsistency|
Preterm Birth (<37 weeks)
N = 17,943,871
|After adjustment, increased odds of PTB with cannabis use during pregnancy||Downgraded 1 level each for RoB and inconsistency|
Perinatal mortality (e.g., stillbirth, fetal demise)
N = 14,141,101
|After adjustment, increased odds of perinatal mortality with cannabis use during pregnancy||Downgraded 1 level for RoB and 2 levels for indirectness|
SGA (<10th percentile)
N = 4,582,445
|After adjustment, increased odds of SGA birth with cannabis use during pregnancy||Downgraded 1 level each for RoB and inconsistency|
Abbreviations. RoB: risk of bias; SGA: small-for-gestational age; PTB: preterm birth
GRADE certainty of evidence: Very low ⨁◯◯◯; Low ⨁⨁◯◯; Moderate ⨁⨁⨁◯; High ⨁⨁⨁⨁
- Overall, we found very low to low CoE of the associations of cannabis use in pregnancy and preterm birth, perinatal mortality, and small-for-gestational-age.
- Despite our findings indicating potential perinatal harms of cannabis use during pregnancy, our certainty in them is low. As prenatal cannabis use becomes more commonplace, this review can help guide healthcare providers with counseling, management, and addressing the limited existing safety data.
Gaps in Evidence
- High quality studies that consider formulation and dosing of cannabis, as well as the timing and duration of use, are needed to help elucidate the associations between prenatal cannabis exposure and perinatal outcomes.
- High quality studies that fully report both unadjusted and adjusted data are also needed.
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Suggested Citation: Lo J, Shaw B, Robalino S, Ayers C, Durbin S, Rushkin M, Olyaei A, Kansagara D, and Harrod C. Cannabis Use in Pregnancy and Neonatal Outcomes: A Systematic Review and Meta-Analysis. The Systematically Testing the Evidence on Marijuana Project, 2023; [revised Month YYYY]. Accessed [Month DD, YYYY]. https://www.cannabisevidence.org/evidence-syntheses/cannabis-use-in-pregnancy-copy
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