DENVER (AP) — Marijuana use by pregnant or nursing women might seem like a no-brainer of a bad idea. But a proposal in Colorado to step up such warnings was rejected Tuesday because of concern about limited or inconclusive research on the dangers.

Pot shoppers in Colorado and Washington already receive warnings that the drug shouldn’t be used by pregnant and nursing women.

A Colorado bill proposed going further by requiring pot shops to post signs saying that maternal marijuana use poses risks to unborn children. But the sponsor agreed to scrap the effort Tuesday and try again. His proposal revived an ongoing debate about maternal marijuana use.

Some pregnant women use marijuana to alleviate nausea. Women testified Tuesday that the warnings would have been insulting.