‘Worrisome’ findings tie prenatal cannabis use to adverse maternal health outcomes

Key takeaways:

• Prenatal cannabis use is associated with significantly higher risk for adverse outcomes, including gestational hypertension and preeclampsia.
• The mechanisms behind these associations require more research.

Prenatal cannabis may be linked to multiple adverse maternal health outcomes, study results published in JAMA Internal Medicine suggest.

Potential associations between prenatal cannabis use and the health of pregnant women remain “complex” and warrant further investigation, according to researchers.

“These findings are worrisome, as they add to a growing body of evidence that cannabis is not safe to use during pregnancy,” Kelly C. Young-Wolff, PhD, MPH, a research scientist at Kaiser Permanente, said in a press release. “Previous research has focused on the health of the baby, and the relative lack of research on how prenatal cannabis use impacts maternal health is notable.”

Healio previously reported that prenatal cannabis exposure increased risks for preterm birth, low birth weight and neonatal ICU care admission.

In the current study, the researchers examined 316,722 pregnancies from 250,221 individuals that occurred between January 2011 and December 2019.

They measured prenatal cannabis use through self-reporting using a self-administered questionnaire or via urine toxicology testing that occurred during screening at the onset of the patients’ prenatal care.

Study investigators also assessed the frequency of cannabis use — which included categories of monthly or less use, weekly use, daily use or no use. They also used electronic health record data to determine maternal health outcomes.

Results showed significant associations between any prenatal cannabis use and greater risk for:

• gestational hypertension (adjusted RR = 1.17; 95% CI, 1.13-1.21)
• preeclampsia (aRR = 1.08; 95% CI, 1.01-1.15);
• gestational weight gain less than recommended by guidelines (aRR = 1.05; 95% CI, 1.01-1.08);
• gestational weight gain greater than recommended by guidelines (aRR = 1.09; 95% CI, 1.08-1.10); and
• placental abruption (aRR = 1.19; 95% CI, 1.05-1.36).

Researchers also reported a link between prenatal cannabis use and reduced risk for gestational diabetes (aRR = 0.89; 95% CI, 0.85-0.94) but no association with placenta accreta, severe maternal morbidity or placenta previa.

Some risks varied based on frequency of use. For example, the risk for gestational hypertension decreased from daily (aRR = 1.24; 95% CI, 1.14-1.36) to weekly (aRR = 1.21; 95% CI, 1.11-1.31) to monthly prenatal cannabis use (aRR = 1.03; 95% CI, 0.97-1.1).

Additionally, study investigators found an association between increased risk for gestational weight gain less than recommended by guidelines and weekly cannabis use (aRR = 1.09; 95% CI, 1.01-1.18). Meanwhile, they observed a greater risk for placental abruption among women who reported monthly use or less (aRR = 1.31; 95% CI, 1.03-1.67).

“The findings related to the frequency of use offer an important message for harm reduction,” Lyndsay Avalos, PhD, MPH, a research scientist at Kaiser Permanente, said in the release. “For patients who are not willing to stop using cannabis during pregnancy, decreasing use may pose lower risk of pregnancy complications.”

However, the researchers noted there were several notable study limitations. The general applicability of the findings are limited because the study sample came from a single health care organization in California.

Additionally, the study did not assess other factors of cannabis use — including potency, method of administration, reasons for use or products used.

Researchers concluded that the findings underline a need for further study on potential mechanisms behind the associations, while clinicians should “provide coordinated, nonstigmatizing care and education to support pregnant individuals in making informed decisions about cannabis use.”

References:

• Cannabis in pregnancy linked to some maternal health problems. Available at: https://divisionofresearch.kaiserpermanente.org/cannabis-in-pregnancy-maternal-health-problems/. Published July 22, 2024. Accessed July 23, 2024.
• Young-Wolff K, et al. JAMA Intern Med. 2024;doi:10.1001/jamainternmed.2024.3270.