Meta-Analysis Links Prenatal Cannabis to Smaller Babies
A meta-analysis of 13 studies found that fetal cannabis exposure was associated with 79% higher odds of being small for gestational age and 38% higher odds of low birth weight.
Quick Facts
What This Study Found
Neonates with fetal cannabis exposure had significantly higher odds of being small for gestational age (OR=1.79) and low birth weight (OR=1.38). Results for NICU admission (OR=1.38) and preterm birth (OR=1.29) were not statistically significant, though the upper confidence bounds suggest possible clinical relevance.
Key Numbers
Small for gestational age: OR=1.79 (95% CI: 1.24-2.59). Low birth weight: OR=1.38 (95% CI: 1.05-1.89). NICU admission: OR=1.38 (95% CI: 0.86-2.22, not significant). Preterm birth: OR=1.29 (95% CI: 0.97-1.71, not significant). 13 studies included from 3,390 identified.
How They Did This
Systematic review and meta-analysis searching five databases. Thirteen studies met inclusion criteria after quality assessment using the Newcastle-Ottawa Scale. Pooled odds ratios were calculated using the Mantel-Haenszel method for dichotomous data.
Why This Research Matters
This meta-analysis pools evidence from multiple studies to provide a clearer picture of prenatal cannabis risks. The significant findings for birth size outcomes add confidence to what individual studies have suggested.
The Bigger Picture
The consistent signal for reduced birth size across pooled studies strengthens the case that prenatal cannabis exposure affects fetal growth. The non-significant but potentially clinically relevant findings for preterm birth and NICU admission warrant further research.
What This Study Doesn't Tell Us
Based on 13 studies with varying definitions of cannabis exposure. Could not account for dose, frequency, route, or timing of use. Many included studies relied on self-reported cannabis use, which likely underestimates exposure.
Questions This Raises
- ?Does the route of cannabis consumption (smoking vs. edibles) affect neonatal outcomes differently?
- ?Is there a dose threshold below which fetal growth effects are negligible?
Trust & Context
- Key Stat:
- 79% higher odds of being small for gestational age
- Evidence Grade:
- Strong: systematic review and meta-analysis pooling 13 studies with quality assessment, providing the highest level of observational evidence
- Study Age:
- Published in 2025
- Original Title:
- Fetal Cannabis Exposure and Neonatal Outcomes: A Systematic Review and Meta-Analysis.
- Published In:
- Maternal and child health journal, 29(5), 703-713 (2025)
- Authors:
- Bailey, Anna, Kerr, Whitney, Alhay, Zahra, Rom, Morgan, Hamilton, Sheryl, Campbell, Janis, Kuhn, Katrin, Thompson, David, Reese, Jessica A
- Database ID:
- RTHC-06000
Evidence Hierarchy
Combines results from multiple studies to find an overall pattern.
What do these levels mean? →Frequently Asked Questions
How much does prenatal cannabis increase the risk of a small baby?
The meta-analysis found 79% higher odds of being small for gestational age and 38% higher odds of low birth weight. These are relative increases; the absolute risk depends on the baseline rate in a given population.
Does prenatal cannabis cause preterm birth?
The results were not statistically significant for preterm birth (OR=1.29, 95% CI: 0.97-1.71), meaning the analysis could not confirm an association. However, the upper bound of the confidence interval suggests a possible effect that larger studies might detect.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-06000APA
Bailey, Anna; Kerr, Whitney; Alhay, Zahra; Rom, Morgan; Hamilton, Sheryl; Campbell, Janis; Kuhn, Katrin; Thompson, David; Reese, Jessica A. (2025). Fetal Cannabis Exposure and Neonatal Outcomes: A Systematic Review and Meta-Analysis.. Maternal and child health journal, 29(5), 703-713. https://doi.org/10.1007/s10995-025-04096-5
MLA
Bailey, Anna, et al. "Fetal Cannabis Exposure and Neonatal Outcomes: A Systematic Review and Meta-Analysis.." Maternal and child health journal, 2025. https://doi.org/10.1007/s10995-025-04096-5
RethinkTHC
RethinkTHC Research Database. "Fetal Cannabis Exposure and Neonatal Outcomes: A Systematic ..." RTHC-06000. Retrieved from https://rethinkthc.com/research/bailey-2025-fetal-cannabis-exposure-and
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.