The U.S. perspective
Commenting on the study, M. Camille Hoffman, MD, MSc, a maternal-fetal medicine specialist at the University of Colorado in Aurora, said that the findings likely indicate that legalization has made cannabis users less reluctant to come forward for urgent care. “They cannot really claim that this is equivalent to more use, just that more people are willing to present,” she said. Dr. Hoffman was not involved in the study.
The Canadian results do not align perfectly with what is seen in the United States. “It does suggest that there may be more cannabinoid hyperemesis being coded as hyperemesis gravidarum, which is a pregnancy-specific condition vs. a cannabis-dependence-related one,” said Dr. Hoffman.
Literature in the United States often includes tobacco use as a covariate, she added. “This study does not appear to do that,” she said. “Rather, it uses any substance use. Because of this, it is difficult to really know the contribution of cannabis to the adverse pregnancy outcomes vs. the combination of tobacco and cannabis.”
Finally, she pointed out, the proportion of those presenting for acute care for substance use in the 2 years before conception was 22% for acute care visits for cannabis vs 1% for no acute care visits. “This suggests to me that this was a highly vulnerable group before the legalization of cannabis as well. The overall absolute difference is nine in total per 100,000 – hardly enough to draw any real conclusions. Again, maybe those nine were simply more willing to come forth with concerns with cannabis being legal.”
There is no known safe level of cannabis consumption, and its use by pregnant women has been linked to later neurodevelopmental issues in their offspring. A 2022 U.S. study suggested that cannabis exposure in the womb may leave children later in life at risk for autism, psychiatric disorders, and problematic substance abuse, particularly as they enter peak periods of vulnerability in late adolescence.
As to the impact of legalization in certain U.S. states, a 2022 study found that women perceived legalization to mean greater access to cannabis, increased acceptance of use, and greater trust in cannabis retailers. In line with Dr. Hoffman’s view, this study suggested that legalization made pregnant women more willing to discuss cannabis use during pregnancy honestly with their care providers.
In the United States, prenatal cannabis use is still included in definitions of child abuse or neglect and can lead to termination of parental rights, even in states with full legalization.
“These findings highlight the need for ongoing monitoring of markers of cannabis use during pregnancy after legalization,” said Dr. Myran. He also called for effective policies in regions with legal cannabis, such as increased warning labels on cannabis products.
This study was supported by the Canadian Institutes of Health Research and the University of Ottawa site of ICES, which is funded by an annual grant from the Ontario Ministry of Health and Ministry of Long-Term Care. Dr. Myran reports a speaker fee from McMaster University. Dr. Hoffman reports no relevant financial relationships.
A version of this article first appeared on Medscape.com.