State Senator Alice Forgy Kerr, a Republican who introduced Kentucky’s accommodations bill, said she thought part of the challenge in passing protection rules was the underrepresentation of women in the Legislature. Just four of the 38 state senators are women.

“The hardest sell on these bills, I have to say, are to men,” said Senator Kerr, who also voted for a so-called fetal heartbeat bill that would ban abortions as early as six weeks into a pregnancy , and that a federal judge temporarily blocked in March.

“And what I stressed to them, these pro-life legislators, is that this is a pro-life measure,” she said. “We want our women to have safe pregnancies so they can have healthy babies.”

Inside the Kentucky Senate chamber just before lawmakers voted on the workplace bill, the tension was plain to see. State Senator Dan Seum , a Republican, ultimately voted for it, but only after saying he “can always tell when those on the committee have never owned and operated a business.”

Senator Kerr replied, “It’s also always easy to tell who on these committees have never been pregnant.”

The bill garnered support in large part because of the united front created by groups with typically diverging views. Kate Miller, advocacy director at the American Civil Liberties Union in Kentucky, said her organization isn’t always popular around the State Capitol. But an alliance with the Catholic Conference of Kentucky helped raise the bill’s profile, which in turn attracted attention from business groups like the Louisville Chamber of Commerce.

“They were so invested on this issue,” Ms. Miller said of the church. “That made a really big difference.”