New Study Finds Pregnant Women Who Smoke High-THC Marijuana Risk Health Problems For Their Children

Marijuana, and smoking in general, leads to disproportionate birth defects and future health problems for children born from mothers that participate in these activities while pregnant. That’s according to a new study released Monday in Proceedings of the National Academy of Sciences, a reputable peer-reviewed scientific journal.

The effect on heavy marijuana use by pregnant mothers has previously been found to have negative health consequences for fetuses and newborns, causing effects such as autism, THC relapse and emaciation. But Monday’s report offers insight into longer-term effects on young children whose mothers used marijuana years earlier while pregnant with them.

The study followed 71 women who reported using marijuana during their pregnancy — finding their children had increased levels of stress, anxiety, aggression and hyperactivity. The research also detected genetic alterations in the placentas of pregnant mothers who used marijuana. The study’s three lead researchers, all PhD holders from the New York-based Icahn School of Medicine at Mount Sinai, claimed the mothers’ altered placentas correlated to their children’s health problems.

“More than anything, this was about understanding people’s vulnerabilities and the potential unintended harm that could result from smoking the plant,” said Yasmin Hurd, one of the three lead scientists.

Hurd said children born to women who smoked high-THC marijuana while pregnant produced consistent levels of stress hormone cortisol in their children’s hair samples than those of children born to women who used smoke-free CBD or no cannabis at all. The offspring of THC-using pregnant women also showed higher levels of anxiety and hyperactivity in scientific behavioral assessments.

Placenta samples of mothers who smoked marijuana while pregnant also showed a reduction in some genetic expression related to immune system response, which researchers also contributed to health problems in their children.

Hurd told NBC News that while marijuana use among pregnant women generally appeared to harm their future children more than the children of mothers who did not use the plant during their pregnancy, the study could not determine for certain that a child born from a mother that smokes marijuana while pregnant will have health problems.

The 71 women surveyed were part of a larger research project called the Stress in Pregnancy study, which started 2009 and attempts to develop statistics on pregnancy habits and long-term effects on children.