Legal weed has been available in Colorado for years, but the law will add a new component in 2020.

Starting January 1, cannabis stores in the state will be required to post warning signs urging caution to pregnant customers about the risks of marijuana to newborns.

The law is a sign of weed’s ubiquity; what was once a taboo in a number circles is now an everyday routine for many, including those who are with child. Weed has long been considered as verboten to children as other drugs, including alcohol. The American College of Obstetricians and Gynecologists recommends that doctors should encourage pregnant women to discontinue marijuana use. The U.S. Department of Health and Human Services says plainly: “No amount of marijuana has been proven safe to use during pregnancy or while breastfeeding.”

But the prevalence and changing attitudes toward marijuana has prompted some to wonder if that is indeed the case.

Researchers at the University of Denver are trying to bring clarity to that question. The school announced in October that Pilyoung Kim, a psychology professor at the University of Denver, is leading a team that is studying the effects of cannabis on pregnant mothers and their babies.

Kim said she was inspired to get to the bottom of the matter when she was working on a separate research project on poverty and pregnancy. While working on that study, Kim was confronted with a recurring question: “It’s OK to use cannabis while you’re pregnant, right?”

“We were baffled about what to say to these women,” Kim said in a press release. “There is a limited understanding of the effect of cannabis use on themselves and their babies if they are exposed to cannabis inside the womb.”

Some cannabis shops in Colorado have hailed pot as a useful remedy for pregnant women. A study last year on recommendations given to pregnant women at dispensaries in Colorado, one of the first states to legalize recreational pot, found that 69 percent offered the products as a remedy for morning sickness, and that 36 percent said marijuana is safe to use during pregnancy.

In order to help the nearly 800 Colorado businesses comply with the new law ahead of January 1, the nonprofit Smart Colorado has sent out warning signs to all of the stores throughout the state.

“We determined that the state was not providing signage to help Colorado’s marijuana businesses comply with the new law requiring the warning signs so we took the initiative to mail out signs at no cost to the dispensaries,” said Henny Lasley, executive director of Smart Colorado, as quoted by news station KKCO. “It’s important that these fact-based warning messages be prominently placed to counter widespread misinformation that puts the littlest Coloradans at risk.”