Smoking weed during pregnancy increases the risk of autism

Scientists from the maternity hospital in the Canadian capital Ottawa have evaluated data on cannabis and pregnancy. In doing so, they discovered a potential risk for the babies. Like the team around obstetrician Mark Walker in the journal Nature Medicine reported that if the mothers smoked weed during pregnancy, the children were at a significantly higher risk of developing autism.

Children of smoking mothers have a higher risk of autism

The study is based on data from 2007 to 2012. At that time, statisticians in the Canadian state of Ontario recorded a total of 500,000 births to determine whether the mothers had consumed drugs. Around 3,000 of them reported using cannabis, often in combination with other substances. 13.4 percent had also used cocaine, 11.3 percent took prescribed medication, 4.4 percent methadone and 3.8 percent drank while smoking weed.

Finally, the researchers excluded all children who had died before the age of four and calculated the risk of developing autism. If the mothers used cannabis during pregnancy, four out of 1,000 children developed autism. For children who were not exposed to the drug in the womb, the figure was just 2.42 in 1,000.

Cannabis not safe during pregnancy and breastfeeding

Just because the drug is allowed to consume does not mean it is safe for pregnant or breastfeeding women. However, recent statistics show that the number of smoking mothers is growing. “This is worrying because we know little about how cannabis affects pregnant women and their babies. Parents-to-be should educate themselves about the possible risks, and we hope studies like ours help here,” says lead author Mark Walker.

Cannabinols are important messenger substances in the embryo

Doctors suspect that cannabis disrupts the messenger system in the embryo. The intoxicating agent tetrahydrocannabinol (THC) crosses the placenta and enters the growing child’s circulation. However, there is a sensitive endocannabinoid system that is central to the development of the nervous system. It would be disturbed by the THC. Previous studies had also shown that cannabis increases the risk of premature birth.

Update 8/12: In an earlier version of this post it was said that there is a sensitive system of endogenous cannabinoids in the embryos. In order to avoid misunderstandings, we have replaced this with the correct technical term “endocannabinoid system”.


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