Researchers at the Ottawa Hospital Research Institute found that cannabis use during pregnancy may increase the risk of delivering the child early. The study, which was published Tuesday in the Journal of the American Medical Association, evaluated 661,617 pregnancies, among them 9,427 women who said they were cannabis users. Twelve percent of the pregnant cannabis users experienced preterm births, compared with only six percent of non cannabis users.
Still, some caveats are in order. The researchers said that among those who used cannabis during pregnancy, there were plenty of additional risk factors: 59 percent used tobacco, while nearly 20 percent used alcohol. Another 11 percent said they also used opioids. Among the women who said they only used cannabis and no other substances, the rate of preterm birth stood at 9.1%.
“It may be that cannabis exposure is associated more strongly with early and moderate preterm births as opposed to very preterm births, which may have different risk factors including infection, pregnancy-induced hypertension, or incompetent cervix,” the authors wrote. “The risk of preterm birth associated with cannabis exposure was statistically significant in subgroups of women who only used cannabis and no other substances, and among women using tobacco. There was