Cannabis is a widely used psychoactive drug worldwide, and its popularity is growing: The U.S. market for recreational cannabis sales could surpass US$72 billion by 2023.

As of early 2023, 21 U.S. states and the District of Columbia have legalized cannabis for recreational use for people age 21 and up, while 39 states plus the District of Columbia have legalized it for medical use.

The growing wave of legalization and the dramatic increase in cannabis potency over the past two decades have raised concerns among scientists and public health experts about the potential health effects of cannabis use during pregnancy and other vulnerable periods of development, such as the teen years.

I am a developmental neuroscientist specializing in studying what’s known as the endocannabinoid system. This is an evolutionarily ancient system found in humans and other vertebrates that produces natural cannabinoids such as THC and CBD.

Cannabis and its constituents interact with the body’s endocannabinoid system to product their effects. THC and CBD are the most commonly known cannabis extracts and can be synthesized in a lab. My lab also studies the risks versus potential therapeutic value of cannabis and cannabinoids.

People often assume there’s no risk when using cannabis or cannabinoids during vulnerable periods of life, but they’re basing that on little to no data. Our research and that of others suggests that cannabis use during pregnancy and adolescence can present myriad health risks the public should be aware of.

More and more pregnant people are using cannabis today compared with a decade ago, with some studies showing that nearly 1 in 4 pregnant adolescents report that they use cannabis.

Many cannabis-using people may have not known they were pregnant and stopped using when they found out. Others report using cannabis for its touted ability to ease pregnancy-related symptoms, like nausea and anxiety. However, studies do not yet confirm those health claims. What’s more, the potential harms are often downplayed by pro-cannabis marketing and messaging by dispensaries, advocacy groups and even midwives or doulas.

In addition, physicians and other health care providers often are not knowledgeable enough or don’t feel well equipped to discuss the potential risks and benefits of cannabis with their patients, including during pregnancy.

While research shows that most people who are pregnant perceive little to no risk in using cannabis during pregnancy, the data show there is clear cause for concern. Indeed, a growing number of studies link prenatal cannabis exposure to greater risk of preterm birth, lower birth weight and psychiatric and behavioral problems in children. These include, for example, difficulties with attention, thought, social problems, anxiety and depression.

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