When she arrived in Congress last year, Representative Anna Paulina Luna, a hard-right Republican from Florida, joined the rest of her party in staunchly opposing proxy voting, a practice adopted by House Democrats to allow for remote legislating during the pandemic.

Then, in August, she gave birth to her first child and her perspective changed. Now, Ms. Luna is pressing to allow new mothers in Congress to stay away from Washington immediately after giving birth and designate a colleague to cast votes on the House floor on their behalf.

Given Republicans’ deep opposition to proxy voting, the bill Ms. Luna plans to introduce on Tuesday to make the change faces long odds to even be given a floor vote. But it raises a novel issue for a male-dominated institution where the average age is nearly 58 — a place that is largely exempt from workplace laws and is still behind in bringing some of its arcane practices in line with modern expectations.

Ms. Luna, 34, is only the 12th member of Congress to give birth while in office. Despite her intention to have what she referred to as an all-natural “granola” delivery and quickly return to her duties on Capitol Hill, things did not go according to plan. She suffered from pre-eclampsia and had to have labor induced, then experienced a difficult delivery and developed mastitis afterward. Pumped full of blood-pressure medication and antibiotics, she was prohibited by her doctor from traveling.

Her plans for an immediate return to Washington were foiled and Ms. Luna was grounded in St. Petersburg as the House faced crucial votes on a stopgap spending plan to avoid a government shutdown, which she vehemently opposed. She was still out when the House took its historic vote to oust Speaker Kevin McCarthy. (She won’t say how she would have voted on that one, calling it “old history.”)

Still smarting about what she considered the unfairness of it all, Ms. Luna was inspired to draft the bill she is introducing this week. It would effectively grant new mothers in Congress six weeks of maternity leave from voting, making an exception to House rules that allows them to vote by proxy during that period.