Using cannabis while pregnant isn't as dangerous as we believe

Conclusions drawn from individual studies sometimes extend too far beyond the actual data

Angela Stelmakowich, The Growth Op 2 minute read June 8, 2020

“Cognitive performance scores of cannabis-exposed groups overwhelmingly fell within the normal range.” / Photo: evgenyatamanenko/Getty Images

According to a review of studies from the last three decades, cannabis isn’t as detrimental to a child’s cognitive development in pregnant mothers as was previously assumed.

The review, published in Frontiers in Psychology, found that “current evidence does not suggest that prenatal cannabis exposure alone is associated with clinically significant cognitive functioning impairments.”

Fewer than five per cent of studies exploring the issue showed any statistical difference between children’s scores on cognitive tests, whether better or worse, according to Forbes.

“Despite limited data demonstrating pronounced negative effects of prenatal cannabis exposure, popular opinion and public policies still reflect the belief that cannabis is fetotoxic (causes degenerative effects in a developing fetus),” authors write. “Cognitive performance scores of cannabis-exposed groups overwhelmingly fell within the normal range.”

Individual studies, on which legal and medical policies have been based, were given too much weight absent a fuller review. “The studies reviewed show that subtle differences in the cognitive performance between children who had been exposed to the drug prenatally and controls do exist, but the conclusions drawn sometimes extend too far beyond the actual data,” researcher write.

Though small differences between groups may exist, the differences do not indicate evidence of impairment.


“There’s an assumption that even though children are born healthy and normal, there’s an impact that we can’t see, that we just have to wait for them to grow up to see the impairment,” Dr. Ciara Torres, the study’s lead author and an assistant professor of psychology at Columbia University, told Forbes.

In the past, the belief that cannabis was harmful to a fetus has resulted in mothers being incarcerated or children being removed from homes. While the stigmas attached to cannabis use aren’t going to disappear overnight, having a more fulsome picture of the extent to which prenatal cannabis exposure produces clinical consequences on offspring “could have important public health and policy implications,” researchers conclude.

Want to keep up to date on what’s happening in the world of cannabis?

Subscribe to the Cannabis Post newsletter for weekly insights into the industry, what insiders will be talking about and content from across the Postmedia Network.