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Women who use cannabis during their pregnancy have a higher risk of giving birth to children with autism spectrum disorder (ASD), according to the findings of a study published this week in the journal, Nature Medicine.

The researchers found that “children with prenatal cannabis exposure had an increase of 50 percent in the risk of an autism diagnosis over the study period, and these associations were robust after controlling for confounding,” wrote Daniel Corsi PhD of the University of Ottawa and his colleagues.


The researchers reviewed the health outcomes of some 500,000 children born in Ontario between April 1, 2007 and March 31, 2012, linking pregnancy data from Ontario’s birth registry to health administrative databases in other provinces across Canada. A total of 0.6 percent of the mothers reported using cannabis while pregnant.

The researchers monitored the health outcomes of the children who were born for an average 7.4 years, during which 2.2 percent of those who mothers used cannabis during their pregnancy were diagnosed with ASD compared to 1.4 percent among all children.

After adjusting for age, income and other substance use, the researchers found that women who used cannabis during pregnancy had 1.5 times the risk of giving birth to a child with ASD.

In addition, cannabis use during pregnancy was associated with 1.1 times the risk of giving birth to a child who later is diagnosed with ADHD (attention deficit hyperactivity disorder), and 1.2 times the risk of a learning disorder (LD).

Nevertheless, the researchers said these risks were not statistically significant after adjusting for other variables.

“Although findings of an increased risk for childhood neurodevelopmental disorders are of substantive interest, we emphasize a cautious interpretation,” Corsi and colleagues wrote.

Children with ASD Treated with Cannabidiol
In Israel, some children with ASD are being treated with oral drops of cannabidiol (CBD) in a research study conducted by a team from Assaf Harofeh Medical Center, Sackler Faculty of Medicine and Tikun Olam.

The findings showed that aggressive behavior, hyperactivity, sleep problems and problems with anxiety were reduced and behavior improved in the majority of children who received the cannabidiol (CBD) drops in a formula of 30 percent CBD to 5 percent THC, 20:1.

Since the completion of this study, a number of children with Autism Spectrum Disorder are being treated with this formula.

Cannabis Use for HG in Pregnancy?
Cannabis has been used to control nausea in pregnancy in some cases despite the concern about the possible effects of the substance crossing the placenta. According to an article published Gideon Koren and Rana Cohen in January 2020 edition of the Rambam Maimonides Medical Journal,”Cannabis has been known to possess antiemetic effects and there are several medicinal cannabinoids used as antiemetics for cancer chemotherapy.”

Although its favorable use for hyperemesis gravidarum, or HG has been described in social media, the authors write, “only a few papers could be found in the medical literature.”

One of those was a study by Westfall et al. in 2006, reporting on cannabis use for HG in 59 women. Of those, 40 of the women used cannabis to treat their nausea, and 37 considered the treatment to be “extremely effective” or “effective” in controlling their symptoms.

In their current study, the researchers evaluated four HG cases at the Motherisk clinical and research program at Yitzhak Shamir Medical Center in Be’er Ya’akov, Israel, following cannabis use, all of whom reported “highly significant” improvement of their symptoms.

“Based on these four cases, cannabis appears to be an effective drug for HG,” the authors wrote, “and should be further researched in controlled studies… this four-case series is the first academic report with objective and validated measures of response.”