New Study Finds Cannabis May Be 'Unsafe' For Pregnant Women

There's now more evidence that cannabis may not be safe for pregnant women to use.

A newly published study in the Journal of the American Medical Association finds that women who use cannabis during pregnancy could be at higher risk for preterm birth. The findings add to prior research that suggests cannabis use can increase the risk of stillbirth and affect brain development.

These studies come as cannabis use among pregnant women is rising, with cannabis dispensaries even marketing the drug as a natural treatment for morning sickness and pain during pregnancy.

Michael Silverstein, a pediatrician at Boston Medical Center's Grayken Center for Addiction, penned an editorial titled "Cannabis Use in Pregnancy: A Tale of 2 Concerns" to accompany the new study. He spoke with us about the research and the use of cannabis and other substances during pregnancy.

The interview has been lightly edited for clarity.

Your editorial takes up two recent studies about cannabis use in pregnancy. What would you say is the overall message?

The overall message from the first of the two studies is that cannabis use in pregnancy has increased over the last 15 years. It's increased mostly from non-medical cannabis use, with predominant use in the first trimester.

The second study is the more complicated study that looked at a cohort of Canadian women and demonstrated an increased risk of preterm delivery among women who report cannabis use in pregnancy.

But the risk seems relatively small — less than 3%, is that right?

The difference in risk groups when you adjust for potential confounders was just under three percent. But when you look at what's called a relative scale, it came out to a 41% increase. Some people like to look at absolute differences, and some people like to look at relative differences. But on either score, the risk did increase with reported cannabis use.

Some dispensaries are actually touting the use of marijuana to pregnant women saying it can ease, for example, symptoms of morning sickness, it can help with pain, and it's a more natural solution than, say, prescription painkillers. So what do you do about that perception that marijuana use or cannabis use is safe for pregnant women?

Yeah, I think that's an excellent point. Whereas the history of cocaine use in pregnancy was a history of exaggeration, I think what we're looking at here is a history of misperception of safety. I would argue that marketing cannabis or cannabis products as a treatment for morning sickness based on these data is irresponsible.

How do you compare the use of cannabis with the use of other substances as a medical professional?

I think there's no perfect metaphor or perfect comparison. There are some people who look at the data on alcohol and say, "Really, those data apply to heavy drinking and not to the occasional glass of wine with dinner." There are other equally reasonable interpretations that say, "Hey, there's no safe level here," so err on the side of caution and don't drink during pregnancy. The lesson of [studies about] cocaine is a lesson of racism that took science and cast aspersions over large populations of predominantly minority children.

Is there one main message you would say that you'd like folks to take away from this?

I would say there are two main messages. The first is that cannabis use in pregnancy is likely unsafe. Full stop.

The second message is even when the science is good, there's that next layer of what society and the medical community and public health communities do with those data. And that's more a lesson of history than it is of science. Medical and public health communities and society, in general, should be very careful about how this is discussed. We should be very careful not to pass judgment on populations of people.