Marijuana sold in stores would have to have labels warning pregnant women and breastfeeding mothers about the health risks for their fetuses and children under legislation passed Tuesday by the Michigan House.
The bills cleared the chamber on 105-4 votes and were sent to the Senate for consideration in the future.
The main sponsor, Republican Rep. Tom Albert of Lowell, cited "alarming studies" showing that too many women continue to use marijuana while they are pregnant.
"It's just pretty shocking that someone would make that choice. We want to make sure that they have the right information," he said.
The use of marijuana for recreational and medical purposes is legal in the state. Though there is a lack of research on the short- and long-term effects of marijuana on a fetus, some studies show that children exposed to marijuana before birth may sustain harm to the developing brain, according to an analysis by the nonpartisan House Fiscal Agency.
The legislation also would require that an informational pamphlet be made available at every point of sale. It would include safety information related to use by minors and include the poison control hotline number.
Albert said he doubts the warning label would deter "a very hardened drug user," but it could make moderate users think twice — saying similar labels on alcohol have had a positive effect.
One of the four legislators who voted against the bills, Republican Rep. Beau LaFave of Iron Mountain, argued putting warning labels on everything makes them less effective.
"Most people don't read through that stuff," he said.