It’s safe to say that most baby books don’t tell pregnant women to sign up for marijuana studies, but the University of Washington is nonetheless recruiting.

The study is looking at whether prenatal marijuana use impacts infants’ brain development, outside of the influence of alcohol, tobacco and other drugs. Called the “Moms + Marijuana” study, the pregnant women will have their marijuana use tracked from the first trimester and until six months in to see if their infants’ brain are altered in any way.

“The very few investigations that have studied prenatal cannabis exposure and infant brain development have all involved women who are polysubstance drug users. No one has looked at marijuana use exclusively,” UW radiologist Dr. Natalia Kleinhans said. “This study will also involve periodic drug testing during pregnancy to verify in real time that moms aren’t using other drugs, rather than relying on the mother’s self-report after the child is born.”

Many of the studies that have focused on prenatal cannabis exposure have tended to involve women who were using multiple drugs, whereas this one will isolate the impact of marijuana use exclusively, in this case in subjects who use it at least twice a week and primarily to mitigate morning sickness. They’ll be compared against a control group of pregnant women who will not use any marijuana, alcohol, or tobacco.

“This study is targeting a very specific population of women who are using marijuana to manage their symptoms while they’re pregnant,” Kleinhans said. “There’s little research to back up the medical and public health advice they’re getting to stay away from pot to control nausea.”

Seventy women are being recruited for the study, who will be required to report weekly marijuana use and only purchase it from licensed sellers. At six months, the infants will undergo MRI scans of their brains to study any developmental and behavioral impacts. What remains to be seen is whether the parents ever tell their children.