Cannabidiol (CBD), the component in cannabis often used for therapeutic treatments, is increasingly being used during pregnancy as a means of managing symptoms such as nausea, anxiety and sleep. Though the public perception is that CBD – particularly when consumed orally – is safer and helpful for symptom management, little is known about the impact of CBD on pregnancy.
A new study from McMaster University researchers fills that gap in knowledge and has uncovered potential risks, including impaired fetal growth, associated with the use of both tetrahydrocannabinol (THC), the primary psychoactive component of cannabis, as well as CBD, during pregnancy.
The research, published in eBioMedicine, part of The Lancet Discovery Science, on Feb. 05, 2025, found oral cannabis use from early to mid-pregnancy was associated with impaired fetal growth and changes in the placenta, as well as changes in aggression, activity levels and learning ability in offspring.
“The use of cannabis during pregnancy is rising in Canada. Most previous studies focus on exposure to cannabis smoke or just the psychoactive component of cannabis (THC), leaving other cannabis ingredients and methods of consumption understudied. However, consuming cannabis orally or only using other cannabis ingredients like CBD, is often perceived as safer despite this lack of evidence. Our study is shedding light that there’s a possibility that CBD might also be harmful in the pregnancy,” says Tyrah Ritchie, who led the study while completing her master’s degree in the Medical Sciences program at McMaster University and with the McMaster Immunology Research