WARNING! Medical Cannabis Use During Pregnancy Increases Risk of Autism In Children
: Researchers from Ottawa in the largest study of its kind have discovered that children of mothers who reported using cannabis during pregnancy had a 50% increased risk of developing autism spectrum disorder (ASD), compared with children who weren’t exposed to cannabis in utero, even after controlling for confounding factors.
The research findings highlight that women who are thinking of using medical cannabis or even non-prescribed recreational cannabis during pregnancy should be aware of the potential risks of the drug, and talk to a healthcare provider.
The research findings were published in the journal: Nature Medicine https://www.nature.com/articles/s41591-020-1002-5
Dr Daniel Corsi, PhD, epidemiologist at the Ottawa Hospital and BORN Ontario, which is affiliated with the CHEO Research Institute who is also the first and corresponding author of the study told Thailand Medical News, “In the past, we did not have proper data on the effect of cannabis on pregnancies. This is one of the largest studies on this topic to date. We hope our findings will help women and their health-care providers make informed decisions.”
Unfortunately, recreational use of cannabis is now legalized in Canada, and expectant parents may think that cannabis can be used to treat morning sickness.
In reality legalization of cannabis does not mean it’s safe for individuals who are pregnant or breastfeeding.
Health Canada and the Society of Obstetricians and Gynaecologists of Canada recommend against these populations using cannabis, and health warnings to this effect appear on cannabis packaging.
To make matters worse, certain women who are using medical cannabis for other conditions do not update their doctors when they are in the early stages of their pregnancy and still continue taking medical cannabis.
It has been found that cannabinoids, including tetrahydrocannabinol in cannabis, readily cross the placenta and can enter the fetal bloodstream, the researchers commented.
Also human and animal studies suggest that disruption of endocannabinoid signaling may interfere with normal neuronal wiring, and this could have implications for fetal neurodevelopment. “Exposure to cannabinoids while in utero can disrupt the fetal endogenous cannabinoid signaling system, which has several roles in embryo development.”
Although past research have indicated that maternal cannabis use during pregnancy is linked with decreased concentration and attention in their offspring, “… data on long-term follow-up of children with exposure to cannabis in utero are currently limited,” the team continued. “There is a need for larger studies that can adequately control for confounding in cannabis-outcome associations.”
Dr Mark Walker, MD, chief of the department of obstetrics, gynecology and newborn care at the Ottawa Hospital, Professor at the University of Ottawa, and senior author on the study commented, “Despite these warnings, there is evidence that more individuals are using cannabis during pregnancy. This is co
ncerning because we know so little about how cannabis affects pregnant women and their babies. Parents-to-be should inform themselves of the possible risks, and we hope studies like ours can help.”
In order to look for any association between cannabis exposure in pregnancy and neurodevelopmental outcomes in childhood, the study team turned to the BORN birth registry, and reviewed data from every birth in Ontario between 2007 and 2012, before recreational cannabis was legalized. Of the half a million women in the study, about 3,000 (0.6%) reported using cannabis during pregnancy.
The study team had previously found that cannabis use in pregnancy was linked with an increased risk of preterm birth. In that study, they saw that women who used cannabis during pregnancy often used other substances including tobacco, alcohol, and opioids.
In this new study, the researchers specifically focused on 2,200 women who reported using only cannabis, and no other substances, during pregnancy.
The study results showed that babies born to this group still had an increased risk of autism compared with those who did not use cannabis. The incidence of ASD was 4 per 1000 person-years among children exposed to cannabis in pregnancy, compared to 2.42 among unexposed children.
The team reported, “… the primary association between maternal cannabis use and ASD persisted in sensitivity analyses by other substance use, income, and preterm birth.”
Significantly, there was also a tentative link between prenatal cannabis exposure and an increased risk for children developing intellectual disabilities, learning disorders, and ADHD. However, the associations were smaller in magnitude ie 11–22%—than those between maternal cannabis use and offspring autism, and “did not attain statistical significance at conventional levels are matching and covariate adjustment,” the authors stated.
The study team does not know how much cannabis the women were using, how often, at what time during their pregnancy, or how it was consumed. They also noted that while they tried to control for other factors that could influence neurological development, their study showed an association, and could not demonstrate cause-and-effect.
The team said, “Although findings of an increased risk for childhood neurodevelopmental disorders are of substantive interest, we emphasize a cautious interpretation given the likelihood of residual confounding.”
The Canadian team warned that women who are thinking about or currently are using cannabis during pregnancy should talk to their healthcare provider to help make an informed choice about what is best for them and their baby.
While the research team acknowledged a number of limitations to their study, they nevertheless concluded, “In this large retrospective cohort, we found that children with mothers who reported cannabis use in pregnancy were at higher risk for ASD diagnosis. Further study is needed on the amount and timing of cannabis use in pregnancy and childhood health outcomes and following the legalization of cannabis in many jurisdictions.”
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