Cannabis Use During Pregnancy ‘Is Not Safe’

A new study is adding to the body of evidence that smoking cannabis while pregnant could harm both the pregnant person and their unborn child.

In the study funded by the National Institutes of Health and published Tuesday in JAMA, researchers from the University of Utah found that people who used cannabis, measured by if they had detectable cannabis levels in their urine, had a higher rate of pregnancy complications compared to those who did not. 

The research included 9,257 participants from across the country. Out of this group, 610 used cannabis while pregnant; 197 people only used it during the first trimester while 413 used it beyond the first trimester. 

They then analyzed how many participants had what the researchers determined to be an unhealthy pregnancy outcome, which included babies that were smaller than expected, preterm births, stillbirths, or abnormal blood pressure during pregnancy.

Researchers found that the percentage of unhealthy pregnancy outcomes was higher in the group that used cannabis while pregnant. Out of 610 people who used cannabis, more than a quarter of them had some kind of complication, compared to about 17% in the much larger group that did not use cannabis – a difference of more than 50%. 

People who used cannabis only during the first trimester had a slightly lower percentage of complications compared to the people who used it beyond the first trimester: the complication rate was about 24% in the first trimester group, and almost 27% in the continued use group.

“Cannabis use is not safe,” said Robert Silver, M.D., one of the study’s authors, in a press release. “It increases the risk of pregnancy complications. If possible, you shouldn’t use cannabis during pregnancy.”

Many people think that using cannabis while pregnant doesn’t pose a risk, and this group has only grown. The authors say that conflicting information may make it difficult to assess what the true risk is.

“There’s so much information out there—discussion and social media channels and on the Internet—about cannabis use and pregnancy,” said Torri Metz, M.D., lead author of the study, in a press release. “I think it’s hard for patients to understand what they should be worried about, if anything.”