Is Marijuana Safe During Pregnancy?

• By: Becky Striepe

Is it safe to use marijuana while you’re pregnant? The short answer is that we don’t know yet, because marijuana use during pregnancy has been difficult to study. Thanks to marijuana law reform, though, that is changing.

University of Colorado researchers are looking at how marijuana use impacts pregnancy. They’re using survey data to find pregnant women who are already using marijuana, then studying the health of their babies. The lead on the study is Torri Metz, a University of Colorado Hospital OB who received a grant to study marijuana’s impacts on pregnancy.

Now that marijuana is legal in Colorado, they’re seeing more honesty in self-reporting. This kind of study was difficult to do until recently, but Colorado women now seem to either feel more comfortable talking about their marijuana use or just have more access to pot. Metz told the Denver Post, “I am seeing more and more self-reported marijuana use in the clinic. I don’t know if this is a reflection of women using more marijuana or of the women being more willing to tell us about their use.”

Previous research on marijuana use during pregnancy has yielded some conflicting data, as Metz pointed out in the interview. “If you look at the literature now, you find very mixed results. About half of the studies say there is an association between marijuana use and adverse outcomes. About half say there is no association.”

So, what does some of the previous research say about marijuana and pregnancy? As Metz pointed out, past studies had mixed results. One large-scale study in the 80s found no link between marijuana use and birth defects. A 2014 study, however, did find a link between pot and anencephaly, a neural tube defect.

Women who smoked pot during pregnancy also tended to also smoke cigarettes, which cause their own negative effects on fetuses. That can be hard to control for, because researchers can’t exactly ask pregnant nonsmokers (or any women) to start smoking or eating pot, just to see what happens to their babies.

Studying marijuana’s impacts on pregnancy may seem like a waste of time and money, but since women are using marijuana while pregnant, it’s an issue worth looking at more closely. It’s hard for doctors to counsel patients properly without solid evidence about how pot impacts pregnancy.

There’s another important reason to take a new look at marijuana and pregnancy: most of the research on pot and pregnancy happened in the 80s, and 1980s pot was just different from 2016 pot. Marijuana today is stronger and contains more of certain compounds that may be harmful to developing fetuses, specifically to their brain development.

Right now, Metz and the other University of Chicago researchers on this project are working on developing the questionnaire for new moms.