Cannabis use in early pregnancy associated with adverse outcomes

Cannabis use early in pregnancy was associated with adverse placenta-mediated maternal and neonatal outcomes, according to findings presented at The Pregnancy Meeting.

“Best estimates indicate that at least one in 15 pregnant individuals use cannabis,” Torri D. Metz, MD, MS, an associate professor at the University of Utah Health in Salt Lake City, said during the presentation. “Given the high prevalence of use and need to counsel patients about cannabis use in pregnancy, more data are needed to rigorously assess the relationship between maternal cannabis use [and adverse pregnancy outcomes] so that patients can make informed decisions about use.”

For this ancillary analysis of the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-be (nuMoM2b), Metz and colleagues analyzed pregnancy outcomes and confirmed cannabis use by immunoassay of frozen stored urine samples collected between 6 and 14 weeks’ gestation. Urine samples that were positive on immunoassay were confirmed with liquid chromatography-tandem mass spectrometry.

The primary outcome was a composite of small for gestational age, medically indicated preterm birth, stillbirth and hypertensive disorders of pregnancy.

There were 9,257 nuMoM2b participants included for analyses, 540 (5.8%) of whom had urine samples positive for cannabis. A greater proportion of participants in the exposed vs. unexposed group experienced the composite outcome (27.4% vs. 18.1%; P < .001). Additional analyses showed that cannabis exposure was associated with higher rates of small for gestational age (9.5% vs. 4.1%; P < .001), stillbirth (1.5% vs. 0.5%; P = .003) and hypertensive disorders of pregnancy (15.9% vs. 13%; P = .049).

In propensity-weighted analyses and multiple sensitivity analyses, cannabis exposure was associated with the primary outcome.

“Pregnant people should continue to be advised to abstain from cannabis use consistent with existing guidelines,” Metz said.