Moms-to-be may want to lay off the marijuana, or risk having babies more likely to be anxious or exhibit behavioral problems. That's per a study out of Icahn School of Medicine at Mount Sinai and the City University of New York, which found that kids of women who ingest cannabis before or soon after pregnancy are twice as likely than other kids to exhibit anxiety, aggression, or hyperactivity, according to the New York Times. Per the Miami Herald, the study looked at 322 women, among the many nationwide who choose to use marijuana as a morning sickness remedy, not just a recreational drug. It's a growing trend in expectant women—per a 2016 study in California, around twice as many women reported ingesting cannabis during pregnancy than in 2009.
This, the Times notes, despite 40 years of research that time and again has linked cannabis use during pregnancy with things like low birth weight and cognitive issues. Another concern: today's weed is massively more potent than what people were smoking 40 years ago. “One joint today is like 17 joints in the 1970s,” Dr. Darine El-Chaâr, a maternal-fetal medicine physician at The Ottawa Hospital in Canada, told the Times. Dr. El-Chaâr said studies show that THC, the active compound in marijuana, passes from the mother, through the placenta, and to the fetus. One caveat to the most recent study, though: it merely found the children of the marijuana users were more likely to exhibit behavioral issues--it does not prove that cannabis use caused it.
However, the study did find a possible biological link between pre-natal cannabis use and abnormalities in children. When the placentas of the participating mothers were analyzed, researchers found that the cannabis users' showed "dampened activity in genes that make key immune-related proteins" and immune abnormalities during pregnancy (caused by things like the flu) have, in the past, been shown in some studies to be linked to problems in a child's brain development. (Read more marijuana stories.)