Is it safe to use cannabis during pregnancy? Here’s what Utah researchers found.

A study of cannabis use in more than 9,000 pregnant people across the U.S. found that using the drug during pregnancy can increase the likelihood of stillbirths and other adverse outcomes, according to findings released this week.

Dr. Torri Metz, the study’s author and University of Utah Health’s obstetrics research vice chair, first conceived the research idea about the time Colorado legalized cannabis for recreational use more than a decade ago.

Cannabis use was (and has been) increasing, and she wondered what impacts that could have on pregnancies, she said at a Tuesday news conference. Since the body’s natural cannabis receptors play an important role in placental development, how might the placenta be impacted by outside cannabis use?

Her questions culminated in one of the “largest and most rigorous studies” on cannabis use during pregnancy to date, according to a news release.

That research showed 26% of those who ingested cannabis during pregnancy experienced some kind of adverse outcome related to the placenta, such as stillbirths, high blood pressure, medically induced early labor or giving birth to smaller than normal babies.

Those outcomes happened in just 17% of cases where people didn’t consume cannabis during pregnancy, Metz said.

The study also found that risk decreased as use decreased, meaning that cutting back or “stopping at any point is helpful.” Ideally, Metz said, a patient should abstain entirely.

Metz said her study was unique in that it didn’t rely on self-reported cannabis use, which patients typically underestimate. It instead relied on tracking cannabis metabolites in urine to determine if someone was using the drug.

She added that the study also raises more questions: How are children impacted over time? Do products with higher concentrations of THC impact outcomes? Are the same effects seen when looking at other metabolites, such as CBD products?

While there is still more to learn, Metz said doctors should advise pregnant patients against cannabis, like they would a variety of other substances.

“We ask people not to use alcohol during pregnancy, not to smoke tobacco during pregnancy,” she said. “Similarly, I think that we can have frank conversations with patients about not using cannabis during pregnancy.”

For those who use cannabis to help alleviate nausea or anxiety during pregnancy, Metz said there are safer alternatives, and individuals should talk to their doctor about those options.

Read more about Metz’ study here.