Working women who become pregnant face the daunting task of balancing their careers while nurturing the health of their child.

U.S. Sen. Bob Casey, D-Pa., says that task is too often made more difficult by employers who see pregnancy as a threat to productivity.

To remedy the situation Casey has crafted the Pregnant Workers Fairness Act -- a bill that would update 1978's Pregnancy Discrimination Act. His bill follows the lead of the Americans with Disabilities Act -- demanding that employers provide pregnant workers with "reasonable accommodations" as long as they don't interfere with the job.

Those who champion women's rights say the proposed change is a long time coming because current regulations don't clearly obligate employers to provide moms-to-be with the accommodations their pregnancies often require.

Charmaine Wright, a professor of Medicine at the University of Pennsylvania, often comes up against employers who disregard the advice she proscribes for her patients.

"I'm a doctor who writes a lot of these work notes, for example: please let Mrs. So and So be able to sit down every four hours, please let my patient be able to drink water on the job ... and oftentimes these letters fall on deaf ears," said Wright. "I want there to be some reckoning. I want there to be some action."

Casey says, if passed, his bill wouldn't place an undue burden on small businesses.

"The workplace will be a lot better for the employer if employees have those kinds of basic protections," he said.

The current law only holds employers liable if a pregnant worker can prove that she's being treated differently than another employee of similar stature.

Proponents of Casey's bill say this is a problem for a few reasons. Workers often don't know how their counterparts are treated, they say, and the pregnant worker may face limitations that other workers don't experience.

Casey will introduce the bill in the Senate next week.