Cannabis Use In Pregnancy Linked To A Greater Risk Of Autism

By August 10, 2020 Media Release

Media Release 11 August 2020
In the largest study of its kind, Ottawa researchers have found that children whose mothers reported using cannabis during pregnancy were at greater risk of autism. According to the study, women who use marijuana during pregnancy have a more than 50 percent greater chance to give birth to a child with autism versus non-users. The study also found the risk for other neurodevelopmental disorders was heightened. The findings were published in the prestigious medical journal Nature Medicine. The research team reviewed data from every birth in Ontario between 2007 and 2012, before recreational cannabis was legalised. The researchers had previously found that cannabis use in pregnancy was linked to an increased risk of preterm birth. 

“Legalisation of marijuana has led to major concerns around pregnant mums using the drug, including as a treatment for morning sickness, and an increase in the number of babies being born THC-positive. This is just one of the many health hazards when you legalise a harmful addictive drug and normalise its use in the community,” says spokesperson Aaron ironside.

Marijuana during pregnancy is on the rise in the US. According to a recent, first-of-its-kind General Advisory from the U.S. Surgeon General, past month marijuana use among pregnant women doubled between 2002 and 2017. Furthermore, marijuana use during pregnancy has been linked to lower birth weight, hyperactivity, poor cognitive function, and other long-term consequences.

A 2019 study found that marijuana use doubled among pregnant women between 2002 and 2017 and is most common in the first trimester. Past-month marijuana use increased from 3.4 percent to 7 percent among pregnant women overall. The data came from an analysis of the National Survey on Drug Use and Health between 2002 and 2017, which involved nearly half a million women. And a July 2019 study based in California found that the frequency with which women in California use cannabis in the year before and during pregnancy has increased over time, corresponding with increasing acceptance of cannabis use and decreasing perceptions of cannabis-associated harms. The data indicates that cannabis is used differentially and disproportionately by the young, the poor and racial minorities.

A study in the June 2019 edition Journal of the American Medical Association also reported a sharp increase in the number of pregnant women smoking marijuana and an alarming link between cannabis use and preterm births, defined as 37 weeks or earlier. Canadian researchers compared the outcomes of birth by 5,639 mothers who reported cannabis use during pregnancy with 92,873 mothers who said they didn’t use it. The authors concluded marijuana is “likely unsafe” because pre-term births were twice as common in marijuana users vs. non users.

If a woman consumes marijuana while pregnant, their child is more likely to suffer sleep problems as much as a decade later, according to a new University of Colorado Boulder study of nearly 12,000 youth. Published in Sleep Health: The Journal of The National Sleep Foundation, the paper is the latest to link prenatal cannabis use to developmental problems in children and the first to suggest it may impact sleep cycles long-term. Those who used marijuana frequently were more likely to report somnolence symptoms (symptoms of excess sleepiness) in their children, such as trouble waking in the morning and being excessively tired during the day.

“These are the health consequences that voters must consider when they consider whether to legalise and normalise drug use. We say it’s not worth the risk.”