New review sheds light on risks of cannabis use in pregnancy

As the global trend toward cannabis legalisation continues, the prevalence of cannabis use among pregnant women is on the rise, raising concerns about its impact on foetal development.

A new study led by researchers in the Faculty of Medicine at Hebrew University in collaboration with the Hadassah Medical Center, sheds light on the potential long-term neuropsychiatric risks associated with prenatal cannabis exposure.

The comprehensive systematic review and meta-analysis involving over 500,000 participants from observational studies, aimed to assess the potential risks posed by prenatal exposure to THC, the primary psychoactive compound in cannabis. THC is known to cross the placenta, potentially affecting the developing foetal brain.

The findings indicate no significant association between prenatal cannabis exposure and an increased risk of autism spectrum disorder (ASD), psychotic symptoms, anxiety, or depression in offspring. 

However, the study did identify a slight increase in the risk of attention-deficit/hyperactivity disorder (ADHD) and a heightened vulnerability to cannabis consumption in children exposed to cannabis in utero.

“These findings suggest that while prenatal cannabis exposure does not appear to significantly increase the risk for many neuropsychiatric disorders, there is still a mild increase in the risk for ADHD and a greater likelihood of cannabis use in the offspring,” said Professor Ilan Matok from the Department of Clinical Pharmacy at the School of Pharmacy at Hebrew University, in a news release.

“This calls for cautious interpretation, as it does not confirm the safety of cannabis consumption during pregnancy.”

Despite many women using cannabis medicinally, the majority of existing studies have only looked at the effects of recreational cannabis, due to the challenges of prescribing in this population. 

Research from 2021 found that many women who consumed cannabis during pregnancy did so to manage pregnancy-related symptoms and pre-existing conditions,​​ including pain management, anxiety, depression, muscle spasms, nausea or appetite, and sleep.

READ MORE: Medical cannabis and pregnancy – what you need to know

This study marks a significant step forward in understanding the complex relationship between prenatal cannabis exposure and neuropsychiatric outcomes in children. 

However, it also emphasises the importance of continued research in this area, especially given that most of the studies on the subject were conducted between the 1980s and early 2000s, when cannabis was characterised by considerably lower levels of THC content than currently used compounds. 

The researchers warn that findings presented in the current study may potentially underestimate the impact of contemporary prenatal cannabis exposure on the long-term neuropsychiatric outcomes.

As the legal landscape surrounding cannabis continues to evolve, more studies will be essential in guiding public health recommendations.

Professor Matok added: “While our study provides important insights, it is crucial to recognize that these results are not definitive. Pregnant women should be aware of the potential risks, and healthcare providers should continue to advise caution when it comes to cannabis use during pregnancy.”