Prenatal marijuana exposure was linked to smaller birth size even without tobacco use
Among 325 pregnant women, marijuana-only exposure was associated with a 66% higher risk of small-for-gestational-age birth and more than double the risk of very small birth size, independent of tobacco use.
Quick Facts
What This Study Found
Marijuana-only exposure was associated with SGA <10th percentile (43% vs. 26%, aRR 1.66) and SGA <5th percentile (30% vs. 13%, aRR 2.26). Tobacco-only was associated with SGA <5th percentile but not <10th percentile. Co-use effects emerged in sensitivity analysis using cotinine-verified tobacco exposure.
Key Numbers
Sample: 325 mothers. Neither exposure: 46%. Marijuana-only: 11%. Tobacco-only: 20%. Co-use: 23%. Marijuana-only SGA <10th: 43% vs. 26% (aRR 1.66). SGA <5th: 30% vs. 13% (aRR 2.26).
How They Did This
Secondary analysis of the prospective LEAF cohort (2010-2015). Marijuana use assessed by urine THC-COOH testing, self-report, and medical records. Modeled as four exposure groups: co-use, marijuana-only, tobacco-only, and neither. SGA defined using 2017 US natality reference data.
Why This Research Matters
This study used objective biomarker confirmation of marijuana exposure and separated marijuana from tobacco effects, providing clearer evidence that marijuana alone may restrict fetal growth.
The Bigger Picture
With marijuana increasingly perceived as safe during pregnancy, objective evidence linking it to fetal growth restriction is important for prenatal counseling.
What This Study Doesn't Tell Us
Moderate sample size (325). High rates of co-exposure complicate separation of effects. Single urine sample may miss intermittent use. LEAF cohort may not be nationally representative.
Questions This Raises
- ?Is there a dose-response relationship between prenatal THC exposure and birth size?
- ?Do the growth effects persist after birth?
Trust & Context
- Key Stat:
- 2.26x higher risk of very small birth size with marijuana-only exposure
- Evidence Grade:
- Prospective design with biomarker-confirmed exposure, though moderate sample size limits precision.
- Study Age:
- Published in 2022 using data from 2010-2015.
- Original Title:
- Association between Prenatal Marijuana and Tobacco Smoke Exposures and Small for Gestational Age at Birth.
- Published In:
- American journal of perinatology, 39(16), 1726-1734 (2022)
- Authors:
- Abdelwahab, Mahmoud, Klebanoff, Mark A(2), Venkatesh, Kartik K
- Database ID:
- RTHC-03648
Evidence Hierarchy
Enrolls participants and follows them forward in time.
What do these levels mean? →Frequently Asked Questions
Does marijuana use during pregnancy affect birth size?
In this study, marijuana-only exposure was associated with a 66% higher risk of small-for-gestational-age birth and more than double the risk of being very small at birth.
Is the risk from marijuana or tobacco?
Both contribute independently. Marijuana-only exposure showed significant growth restriction even without any tobacco use, using objective urine testing to confirm exposure.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-03648APA
Abdelwahab, Mahmoud; Klebanoff, Mark A; Venkatesh, Kartik K. (2022). Association between Prenatal Marijuana and Tobacco Smoke Exposures and Small for Gestational Age at Birth.. American journal of perinatology, 39(16), 1726-1734. https://doi.org/10.1055/s-0042-1753489
MLA
Abdelwahab, Mahmoud, et al. "Association between Prenatal Marijuana and Tobacco Smoke Exposures and Small for Gestational Age at Birth.." American journal of perinatology, 2022. https://doi.org/10.1055/s-0042-1753489
RethinkTHC
RethinkTHC Research Database. "Association between Prenatal Marijuana and Tobacco Smoke Exp..." RTHC-03648. Retrieved from https://rethinkthc.com/research/abdelwahab-2022-association-between-prenatal-marijuana
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.