Cannabis users had higher risks for hypertensive disorders of pregnancy and placental abruption.

We know little about the effect of prenatal cannabis use on maternal outcomes. In this study from the Kaiser Permanente Northern California health system, researchers compared maternal outcomes in 20,000 users and 300,000 nonusers of cannabis during pregnancies that occurred between 2011 and 2019. Prenatal cannabis use was determined by either self-report or positive confirmed toxicology results following universal pregnancy urine screening.

Key results included the following:

• cannabis users were younger and from lower socioeconomic groups than nonusers; they also had higher rates of mood disorders, substance use disorders and smoking. Analysis of outcomes was adjusted statistically for these differences
• prenatal cannabis use was associated with significantly higher risk for hypertensive disorders of pregnancy (i.e. gestational hypertension [adjusted risk ratio (aRR), 1.17] and preeclampsia [aRR, 1.08]). A dose-­response relation between frequency of cannabis use and risk for gestational hyperten­sion was observed
• prenatal cannabis use also was asso­ciated with higher risk for placental abruption (aRR, 1.19) but lower risk for gestational diabetes (aRR, 0.89)
• cannabis users were more likely than nonusers to have higher-than-recommended gestational weight gain (69% vs 59%).

Comment: Any potentially modifiable risk for adverse maternal health outcomes deserves special attention. Although cannabis use prevalence in this study was 6%, a recent study suggests that cannabidiol use in pregnancy in North America is as high as 20% (Obstet Gynecol 2024; 144: 156­159). A caveat here is that cannabis users and nonusers had sub­ stantially different demographic and behavioural characteristics, and some confounding is inevitable despite statistical adjustment. Nevertheless, I plan to incorporate counselling on cannabis use into routine prenatal discussions.

Marie Claire O’Dwyer, MB BCh BAO, MPH, Clinical Assistant Professor in Family Medicine, University of Michigan Medical School, Ann Arbor, USA.

Young-Wolff KC, et al. Prenatal cannabis use and maternal pregnancy outcomes. JAMA Intern Med 2024 Jul 22; e-pub (https://doi.org/10.1001/jamainternmed. 2024.3270).

This summary is taken from the following Journal Watch titles: General Medicine, Women’s Health, Ambulatory Medicine.