“Women who used cannabis during pregnancy were 1.5 times more likely to have a child with autism,” said the study’s author. Darine El-Chaâr, a maternal specialty specialist and clinical researcher at Ottawa Hospital Research Institute in Canada.
“These are not reassuring findings. We strongly discourage use of cannabis during pregnancy and breastfeeding,” she said.
“On that basis, “I’m not too surprised by these findings,” said El-Chaâr. Fetal brain development occurs at all gestational ages. “
The study, published Monday in the journal Nature, looked at data from each birth in Ontario, Canada, between 2007 and 2012, before recreational marijuana was legalized in Canada in 2017. Of the half a million women in that data pool, researchers then examined the study to 2,200 women who said they only used marijuana during pregnancy, without mixing it with tobacco, alcohol or opioids.
The study did not capture the amount and type of marijuana that women used during pregnancy. The study also did not know when during pregnancy or how often women used it. And although the study could only show association, not cause and effect, researchers said they did their best to eliminate confusing factors.
Weed use during growth of pregnancy
As weeds become legalized and socially acceptable, health care researchers are making moms-to-be think it is good to use to treat morning sickness or recreational use, despite the lack of long-term impact research on a fetus.
Pain management, El-Chaâr said she hears from expectant mothers, is the most common reason for using marijuana.
“It helps in various circumstances they may have like for nausea and vomiting in pregnancy,” El-Chaâr said. “Some people (said) they use (it) for sleep or for stress reduction. Still others use it recreationally; it’s just part of their routine.”
The vast majority of marijuana use was in the first three months of pregnancy, the study found, and was primarily recreational rather than medical.
However, the first trimester can be one of the most sensitive times for developing a fetus’ brain, when it is most susceptible to damage, El-Chaâr said. Studies have found recipients of cannabis in the brains of animals as early as five and six weeks of gestational age, she said.
“You can hypothesize that if there are cannabinoid receptors and the baby’s brain is exposed, it could (have) an effect on brain development,” she said.
What to do
The self-reported prevalence of marijuana use during pregnancy varies from 2% to 5% in most studies, according to the American College of Obstetricians and Gynecologists.
“There is insufficient data to evaluate the effects of marijuana use on infants during lactation and breastfeeding, and in the absence of such data, marijuana use is discouraged.”
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