Study Examines How Cannabis Use during Pregnancy Affects Birth

A study published December 12th, 2023, in the Journal of the American Medical Association looked at how cannabis consumed during pregnancy affected the outcomes of births (1). To establish the importance of the study, which was titled “Cannabis Exposure and Adverse Pregnancy Outcomes Related to Placental Function,” researchers cited the lack of knowledge about how cannabis affects pregnancy, plus the rise in cannabis use among individuals of reproductive age (1).

Researchers from several universities and one laboratory confirmed cannabis exposure during the pregnancies of 9257 participants though frozen urine samples collected during three study visits spaced throughout the trimesters, then analyzed birth outcomes including low birth weight, preterm birth, and stillborn (1). These three birth outcomes were combined into one primary outcome due to their connection to placental function, explained lead study author Torri Metz, obstetrician and associate professor at the University of Utah Health (2).

Of the 610 participants exposed to cannabis, 32.4% were exposed only during the first trimester, and 67.6% were exposed beyond the first trimester (1). Researchers found that the adverse birth outcomes were associated with 25.9% of the exposed group compared to 17.4% in the group that was not exposed (1).

“Looking at any adverse outcome, we saw that people who had stopped use within the first trimester didn’t actually have a statistically significant increased risk [vs.] those who had continued use,” Dr. Metz (3).

The analysis was adjusted for certain characteristics and behaviors, including nicotine use (1).

“In this multicenter cohort, maternal cannabis use ascertained by biological sampling was associated with adverse pregnancy outcomes related to placental dysfunction,” stated the abstract (1). “Cannabis use should be avoided during pregnancy to optimize maternal and neonatal outcomes,” researchers concluded in one of the key points of the study (1).

References

1. Metz, T. D.; Allshouse, A. A.; McMillin, G. A.; Greene, T.; Chung, J. H.; Grobman, W. A.; Haas, D. M.; Mercer, B. M.; Parry, S.; Reddy, U. M.; et al. Cannabis exposure and adverse pregnancy outcomes related to placental function. JAMA 2023, 330 (22), 2191 DOI: 10.1001/jama.2023.21146.
2. Carroll, L. Marijuana use during pregnancy linked to low birth weight, study finds https://www.nbcnews.com/health/womens-health/marijuana-use-pregnancy-linked-low-birth-weight-study-finds-rcna129083 (accessed Dec 18, 2023).
3. Malhi, S. Cannabis use linked to higher risk of poor pregnancy outcomes, study ... https://www.washingtonpost.com/health/2023/12/12/cannabis-use-pregnancy-postpartum-study/ (accessed Dec 18, 2023).