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Research: Cannabis use in pregnancy increases the risk of autism

Experts have been warning for years about cannabis use during pregnancy, but so far there has been no evidence of actual harm to the fetus. Now a new study puts up a significant warning sign. Here are all the details

• Cannabis
• Pregnancy
• marijuana
• autism

Walla! health

In recent years more and more women are smoking cannabis during pregnancy. A 2018 study found that between 2009 and 2016, there was an increase in the number of women whose urine tests were found to be positive for marijuana use around the 8th week of pregnancy, and their rate rose from four to seven percent. This fact worried researchers even then, as doctors do not know enough about the effect of cannabis on the fetus, and it is even more worrying in light of new research findings linking this habit to the risk of autism.

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To the full article

A comprehensive study published this week in the journal Nature found that children of women who used marijuana during pregnancy were 1.5 times more likely to have autism. Researchers from the Research Center of Ottawa Hospital in Canada examined more than 500,000 pregnancies and births between 2007 and 2012. In 2,200 cases, mothers said they used marijuana during pregnancy, without mixing it with tobacco, alcohol or other drugs.

According to the study, a link was found between "cannabis use in pregnancy and the prevalence of autism spectrum disorder in offspring." The researchers found that the prevalence of autism spectrum disorders was 4 per 1,000 among children exposed to pregnant cannabis, compared with 2.42 among children who were not exposed, and hence, that cannabis during pregnancy increases the risk of autism by 1.51.

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Researchers have previously suspected that marijuana use during pregnancy may inhibit the physical and brain development of the fetus in utero, but unlike tobacco and alcohol - in the case of marijuana so far no evidence has been found of a clear and unambiguous link between it and birth defects.

Danger that these researchers have been able to prove in the past regarding cannabis is the fear of premature birth. A study published in 2019 found that smoking marijuana doubles the risk of preterm birth - before week 37 - which puts the fetus at risk. The study findings showed that 12 percent of births in the case where the mother smoked cannabis occurred earlier than expected, compared with 6 percent in women who did not smoke. The study also found that women who smoked cannabis during pregnancy had higher rates of placental abruption, a rare but serious complication in which the placenta that provides oxygen and nutrients to the fetus separates from the uterus. In addition, infants of mothers who smoked cannabis during pregnancy required higher percentages (19.3) in intensive care compared with children of non-smoking mothers (13.8).

Not unequivocal proof, but definitely cause for concern

While Canadian research is considered relatively large and comprehensive, it has quite a few drawbacks. It does not take into account the amount and type of marijuana used by the women, when it happened during pregnancy or how often. The study also does not conclusively prove that marijuana use during pregnancy causes autism, but only that there is a link between the two factors.

Still, the researchers believe that there are enough in their findings to call for women to give up cannabis during pregnancy. "These are not reassuring findings," said research author Dr Darin al-Khar, a maternal-fetal medicine expert and clinical researcher at the Ottawa Hospital Research Institute, "We strongly do not encourage cannabis use during pregnancy and lactation."