Cannabis Use and Pregnancy: Insights from a Cohort Study

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A cohort study (1) titled “Prenatal Cannabis Use and Maternal Pregnancy Outcomes” and published July 22, 2024, in JAMA Internal Medicine sought to answer the question, “Is prenatal cannabis use associated with maternal health outcomes during pregnancy?” The researchers examined 316,722 pregnancies from January 2011 to December 2019 that lasted at least 20 weeks, and compiled data from self-reported frequency of cannabis use or toxicology tests.

As stated in the study, researchers found that “prenatal cannabis use was associated with increased risk of gestational hypertension, preeclampsia, weight gain greater and less than guidelines, and placental abruption as well as reduced risk of gestational diabetes. No association was found with eclampsia, placenta previa, placenta accreta, or severe maternal morbidity.”

Some of the limitations noted in the research included the data being sourced only from patients in Northern California health care organizations, resulting in difficulty of generalizing the results to those who are uninsured or outside California, where medical and recreational cannabis use is legal.

The researchers ultimately concluded that, “The results of this study suggest that the association between prenatal cannabis use and maternal health is complex and there is a need for continued research to understand how prenatal cannabis use affects the health of pregnant individuals.” One area in particular where more research was needed, it noted, was the effect of dose, mode, timing, and other characteristics of cannabis use. 

The abstract noted the lack of studies on cannabis use during pregnancy. Similarly, a recent research overview from Ruth Fisher, PhD, noted several difficulties in obtaining data on this subject (2). “It’s unethical to conduct controlled prospective studies on a subject like this, so researchers generally rely on retrospective observational reports,” Fisher explained. “These types of studies have serious flaws. They tend to rely on self-reported data for information on cannabis use. Self-reported data in general is unreliable; self-reported data involving illegal activity or activity potentially perceived as morally questionable, such as using a drug while pregnant, is especially unreliable. Also, not only are the data as to whether or not subjects used cannabis while pregnant unreliable, but there is also generally no information as to the timing, frequency, quantity, concentration, duration, and/or form of cannabis use, all of which matter. Next, retrospective studies generally fail to control for other important factors that may lead to bad outcomes (for example, confounders), including use of other substances (medications, tobacco, alcohol, or other illicit drugs), lack of proper nutrition, stress, and more. Finally, participants in retrospective studies tend to involve non-representative selections of individuals, that is, participants whose outcomes do not generalize to the population as a whole.” The overview examined study effects and outcomes, risks, reasons for use, sources of information on cannabis use during pregnancy, and more.

As the research continues, legal implications of cannabis use and pregnancy also continues. Last week, an Oklahoma Court of Criminal Appeals ruled that women with medical cannabis cards cannot be prosecuted for child neglect for using cannabis while pregnant (3). The ruling came after a woman challenged her charge of felony child neglect after her son tested positive for cannabis at birth.

References

1. Young-Wolff, K. C.; Adams, S. R.; Alexeeff, S. E.; Zhu, Y.; Chojolan, E.; Slama, N. E.; Does, M. B.; Silver, L. D.; Ansley, D.; Castellanos, C. L.; et al. Prenatal cannabis use and maternal pregnancy outcomes. JAMA Internal Medicine 2024 DOI: 10.1001/jamainternmed.2024.3270.
2. Fisher, R. Cannabis Use During Pregnancy. Cannabis Science and Technology. https://www.cannabissciencetech.com/view/cannabis-use-during-pregnancy (accessed July 23, 2024).
3. Bailey, B. Oklahoma court rules that moms who use medical marijuana while pregnant aren’t breaking the law. The Frontier. https://www.readfrontier.org/stories/oklahoma-court-rules-that-moms-who-use-medical-marijuana-while-pregnant-arent-breaking-the-law/ (accessed July 22, 2024).