Pregnancy is not a disability, but pregnant workers can still need protection.

Pregnancy is specifically not covered under the Americans With Disabilities Act, which requires that employers provide reasonable accommodations to disabled employees who need them to do their jobs. This is fine with most pregnant women: the idea that pregnancy is a disability raises hackles. If pregnancy is a disability, then most women (82 percent of women will be pregnant at some point during their lifetime) are periodically less abled than men.

But to have a healthy pregnancy, women must make adjustments — call them accommodations — for the baby they’re carrying. They need to drink more water, and accept that altered balance and an increase in the hormone that relaxes muscles mean a greater risk of accidents from climbing ladders and heavy lifting. Women who are carrying babies in these small ways may need accommodation from their jobs — and in most states, and at the federal level, there is no legal requirement that they get it.

Pregnant women are protected by the federal Pregnancy Discrimination Act, but protection against discrimination does not require accommodation. Sometimes equal treatment is not enough to allow a woman to stay on the job — and no one benefits from pregnant women being forced to choose between her doctor’s advice and her supervisor’s demands.

Federal legislation to be introduced Tuesday by House members from New York and California (including Representatives Jerrold Nadler and Carolyn B. Maloney) is intended to ensure that no woman has to make that choice. The Pregnant Workers Fairness Act, says Mr. Nadler, will “require an employer to make a reasonable accommodation for pregnancy, childbirth, and related medical conditions, unless this creates an undue hardship on the employer.”

The legislation would also prevent employers from using a worker’s pregnancy to deny her opportunities on the job, force her to take an accommodation that she does not want or need, or force her onto leave when another reasonable accommodation could help keep her on the job — all rules that should already be familiar to employers, thanks to the Americans With Disabilities Act.

Not every pregnant woman needs accommodation, and many employers would consider those accommodations “reasonable” without legislation. But the U.P.S. worker denied the “light duty” that was available to injured workers (who then lost her medical coverage when she was placed on unpaid leave), the Walmart employee fired for carrying a water bottle, and the nursing home activity director who asked for help moving tables and pushing wheelchairs and was terminated over the request (even though her fellow employees were already voluntarily assisting her with those jobs) know that not every employer is reasonable, and that sometimes a request that seems small can become something far more. Legislative protection could mean the chance for a pregnant woman to stay both physically and financially more healthy—an outcome with benefits for us all.