Systematically Testing the Evidence on Marijuana

Cannabis Use in Pregnancy and Neonatal Outcomes

Quick Links:  Latest Report | Visual Abstract | Clinician Counseling Video | Summary  | Publication History

Latest Report

The most recent report is available as an author-accepted version of our manuscript published online May 2025 in the journal JAMA Pediatrics.

Visual Abstract

Clinician Counseling Video

How I Talk to Patients About Cannabis Use and Pregnancy

In this video, Jamie Lo M.D., M.C.R., a Maternal-Fetal Medicine clinician and Associate Professor in Obstetrics and Gynecology at Oregon Health & Science University, presents some key messages for clinicians when speaking to patients about cannabis use and pregnancy.

Summary

Cannabis use in pregnancy and neonatal outcomes: A systematic review and meta-analysis

Background
  • 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 the American College of Obstetricians and Gynecologists advise pregnant and lactating individuals to abstain from using cannabis due to concern for potential adverse fetal outcomes.
  • Prior reviews have been limited by lack of adjustment for important confounding factors (e.g., prenatal tobacco use).
  • This review provides a contemporary understanding of the association between prenatal cannabis exposure and fetal and neonatal outcomes after accounting for tobacco use.
Methods

Living systematic review

Search:

(Searched through April 4, 2024)

  • 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: As outlined in our report, the CoE has increased for most of the key outcomes. As this body of evidence will always rely on observational data, it is unlikely that new studies would meaningfully alter conclusions so we will not be continuing literature surveillance. 

Findings

We identified 51 eligible observational studies. In general, we rated these studies as having low to moderate risk of bias (RoB). Because randomized control trials (RCTs) are not ethically possible with pregnant individuals and cannabis use, observational study designs will always inherently limit the RoB of these studies compared to low-RoB RCTs; therefore we downgraded all GRADE certainty of evidence (CoE) ratings one level for RoB, making moderate CoE the highest achievable rating for this evidence base.

Following statistical adjustment, we observed increased odds of LBW (n = 24 studies; moderate CoE), PTB (n = 42 studies; moderate CoE), SGA (n = 21 studies; moderate CoE), and perinatal mortality (n = 16 studies; low CoE) in infants of individuals who used cannabis in pregnancy.

Summary of Findings (GRADE)

Outcome
Number of Studies
Sample Size		 Certainty of the Evidence Relationship Rationale for CoE Rating
LBW (< 2,500g)
24 studies
N = 2,412,060		 ⨁⨁⨁◯
Moderate		 After adjustment, increased odds of LBW with cannabis use during pregnancy Downgraded 1 level for RoB
PTB (<37 weeks)
42 studies
N = 21,131,345		 ⨁⨁⨁◯
Moderate		 After adjustment, increased odds of PTB with cannabis use during pregnancy Downgraded 1 level for RoB
SGA (<10th percentile)
21 studies
N = 7,816,179		 ⨁⨁⨁◯
Moderate		 After adjustment, increased odds of SGA birth with cannabis use during pregnancy Downgraded 1 level for RoB
Perinatal mortality (e.g., stillbirth, fetal demise)
16 studies
N = 16,999,369		 ⨁⨁◯◯
Low		 After adjustment, increased odds of perinatal mortality with cannabis use during pregnancy Downgraded 1 level for RoB and 1 level for indirectness

Abbreviations. LBW: low birth weight; PTB: preterm birth; RoB: Risk of Bias; SGA: small-for-gestational age

GRADE certainty of evidence (CoE): Very low ⨁◯◯◯; Low ⨁⨁◯◯; Moderate ⨁⨁⨁◯; High ⨁⨁⨁⨁

Conclusions
  • Overall, we found low to moderate CoE of the associations of cannabis use in pregnancy and low birth weight, preterm birth, small-for-gestational-age, and perinatal mortality.
  • As prenatal cannabis use becomes more commonplace, this review can help guide healthcare professionals counseling patients on the risks of cannabis use in pregnancy.
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 further elucidate the associations between prenatal cannabis exposure and perinatal outcomes.

Suggested citation: Lo J, Ayers C, Yeddala S, Shaw B, Robalino S, Ward R, Kansagara D. Cannabis use in pregnancy and neonatal outcomes: a systematic review and meta-analysis. The Systematically Testing the Evidence on Marijuana Project. 2021; revised February 2023 and May 2025.  Accessed (Month DD, YYYY). https://www.cannabisevidence.org/evidence-syntheses/cannabis-use-in-pregnancy/

As published in JAMA Pediatrics: https://jamanetwork.com/journals/jamapediatrics/fullarticle/2833505

Publication History

All Versions Last Search Date Publication Date
No further updates expected
Update 1 as submitted to JAMA Pediatrics April 2024 May 2025
Original report as submitted to Cannabis and Cannabinoid Research February 2022 February 2023

Page Last Reviewed: May 2025