(Reuters) — A bipartisan group of U.S. lawmakers introduced legislation on Thursday to boost protections for pregnant workers in response to a recent U.S. Supreme Court ruling that revived discrimination claims by a former United Parcel Service Inc. driver.

Federal law currently prohibits employers from firing, refusing to hire or otherwise discriminating against pregnant women. But while companies are legally required to provide "reasonable accommodations" for disabled workers, the same is not true for pregnant employees.

The bill, sponsored by Sen. Bob Casey, D-Pa., would require employers to make minor modifications to job duties for pregnant employees.

The issue surfaced this year at the Supreme Court, which in March said former UPS driver Peggy Young could proceed with claims that the company discriminated against her by refusing her request to handle lighter packages while she was pregnant.

Though the court revived Ms. Young's lawsuit, it rejected her broader claim that employers must provide the same accommodations to pregnant women that they give to injured or disabled workers.

Lawmakers Thursday said the case highlighted the need for stronger protections in the law.

"No worker should live in fear that her job is at risk simply because she's pregnant," said Sen. Casey.

The group of lawmakers backing the bill includes Sen. Kelly Ayotte, R-N.H., but it was unclear if Republican leadership in Congress would support it. The bill has introduced in the House of Representatives by Rep. Jerrold Nadler, D-N.Y.

According to Sen. Casey's office, nearly 5% of employed women of childbearing age give birth each year, and 62% of pregnant women and new mothers work.

Pregnancy discrimination claims have been on the rise in recent years, according to the U.S. Equal Employment Opportunity Commission. The agency has filed 44 lawsuits against employers including pregnancy-related claims since 2011.

But the claims can be difficult to prove. On Monday, a jury in New Jersey ruled in favor of pharmaceutical giant Merck & Co. in a lawsuit brought by a former department director who said she was passed over for a promotion because she was pregnant.

Merck, accounting firm KPMG and retailer Pier 1 Imports Inc, among others, also are facing class action lawsuits that include similar claims.