Since Canada legalized recreational cannabis in 2018, a study revealed that the rate of acute care for cannabis use during pregnancy in Ontario nearly doubled. The rate of cannabis-related acute care use during pregnancy increased from 11 per 100,000 pregnancies before legalization to 20 per 100,000 pregnancies afterwards, representing an increase of 82%. Severe morning sickness was a significant risk factor for care in the emergency department or hospital, with most acute care events being emergency department visits. The most common reasons for acute care were harmful cannabis use, followed by cannabis dependence or withdrawal and acute cannabis intoxication. The study suggests that cannabis legalization might contribute to and accelerate such trends.

Risks for Newborns

In the US, the rate of cannabis use during pregnancy doubled in 2016-2017 compared to the rate in 2002-2003. A study conducted in Ontario hypothesized that legalizing non-medical cannabis has affected the drug’s use during pregnancy. Acute care for other types of substance use, such as alcohol and opioids, remained steady after cannabis legalization, while acute care for cannabis increased. After cannabis legalization, acute care for mental health conditions, such as anxiety and depression, decreased by 14%. A 2022 US study suggested that cannabis exposure in the womb could 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.

US Perspective

The Canadian results do not align perfectly with the US. Legalization made pregnant women more willing to disclose cannabis use during pregnancy with their care providers. In the US, prenatal cannabis use is still included in definitions of child abuse or neglect and can lead to the termination of parental rights, even in states with full legalization.

To reduce the risks associated with cannabis use during pregnancy, physicians who care for pregnant individuals should consider increasing screening for cannabis use during pregnancy. Repeated non-stigmatizing screening and counseling may be necessary for higher-risk groups, such as those going through severe morning sickness. Effective policies in regions with legal cannabis are needed, such as increased warning labels on cannabis products.

Source: CMAJ