New York Times

WASHINGTON — Peggy Young used to drive for United Parcel Service, delivering envelopes and small packages early in the morning. “I was a dependable, honorable worker,” she said. “I worked when I was supposed to. I did what I was supposed to.”

Then she got pregnant, and her doctor recommended that she avoid lifting anything heavy. The company responded by placing her on unpaid leave.

“I lost my health benefits,” Ms. Young said. “I lost my pension. And I lost my wages for seven months. And my disability benefits.”

She sued under the federal Pregnancy Discrimination Act, and the Supreme Court will hear her case on Wednesday. Women’s rights groups hope that Ms. Young’s case will snap their recent losing streak at the court, which has included decisions on equal pay, medical leave, abortion and contraception.

“We’ve had some very big disappointments recently, but I’m hoping it won’t be a uniform set of experiences,” said Marcia D. Greenberger, a co-president of the National Women’s Law Center. “I hope Peggy Young will break the mold.”

The Supreme Court’s decision has the potential to affect the lives of millions of women, who make up 47 percent of the labor force and often work during and late into their pregnancies. According to the Census Bureau, an estimated 62 percent of women who had given birth in the previous year were in the labor force.

Women are the sole or primary breadwinners in 40 percent of American families with children, according to a Pew Research Center study. Whether employers are required to make accommodations for their pregnancies, women’s groups say, will make a tangible difference in the lives of many families.

UPS has announced that it will change its policy to offer light duty to pregnant women starting in January. “The new policy will strengthen UPS’s commitment to treating all workers fairly and supporting women in the workplace,” said Kara Ross, a spokeswoman for the company.

The case before the Supreme Court, she said, “is really about what the UPS policy was then.” The old policy, she said, “was lawful and consistently applied to our workers.”

The company told the justices that it had no legal obligation to make the kinds of accommodations it recently announced. The lower courts in Ms. Young’s case agreed, with a unanimous three-judge panel of the United States Court of Appeals for the Fourth Circuit in Richmond, Va., saying the pregnancy law does not give pregnant women “a ‘most favored nation’ status.”

“One may characterize the UPS policy as insufficiently charitable,” Judge Allyson Kay Duncan wrote for the court, “but a lack of charity does not amount to discriminatory animus directed at a protected class of employees.”

Ms. Young, speaking in a public relations firm’s conference room here, said it would have been easy for UPS to accommodate her.

The parcels she delivered were so light that the lifting restriction recommended by her doctor was needless. “It’s envelopes or very small boxes,” she said. “They sat in a little basket in a seat next to me. Very rarely was it anything heavy, because it’s very expensive to send that way.”

If something heavy did turn up for an early morning delivery, a co-worker could handle it, Ms. Young said. If the company remained concerned, she said, it could have assigned her less demanding duties.

She said she had worked a second job in the afternoons throughout her pregnancy, delivering flowers. “They were heavier than the packages I would deliver for UPS,” Ms. Young said.

Business groups have filed briefs supporting UPS, saying the pregnancy law did not apply to Ms. Young’s situation. The U.S. Chamber of Commerce noted that many of its members had nonetheless “decided — for a variety of reasons — to offer pregnant employees more than what federal law compels them to provide.”

Ms. Young has attracted a diverse array of supporters, including women’s rights organizations and anti-abortion groups. The federal law, the anti-abortion groups told the justices, “protects the unborn child as well as the working mother who faces economic and other difficulties in bearing and raising the child.”

The Obama administration also supports Ms. Young, a stance that has required it to renounce statements in earlier briefs. The administration’s latest brief included a footnote acknowledging that the federal government “has previously taken the position that pregnant employees with work limitations are not similarly situated to employees with similar limitations caused by on-the-job injuries.”

“That is no longer the position of the United States,” the brief said, though it added that the United States Postal Service “continues to offer different treatment” to its pregnant workers.

Justice Ruth Bader Ginsburg, who was a prominent advocate for gender equality before she became a judge, discussed Ms. Young’s case in an interview with Elle published in September.

The pregnancy law, she noted, was enacted in response to the Supreme Court’s 1976 decision in General Electric Co. v. Gilbert, which ruled that discrimination based on pregnancy was not a form of sex discrimination. That congressional reaction, she said, was similar to one that followed the court’s decision in Ledbetter v. Goodyear Tire & Rubber Co., the 2007 ruling that said Title VII of the Civil Rights Act of 1964 imposed strict time limits for bringing workplace discrimination suits. In response, Congress passed the Lilly Ledbetter Fair Pay Act of 2009.

As for Ms. Young, Justice Ginsburg said, “this was a woman whose doctor told her she couldn’t lift more than, I think, 20 pounds.”

“For people who were temporarily disabled,” she added, “the employer would make an accommodation, but the employer said, ‘We’re not making an accommodation for her because she’s not disabled.’ ”

The case, Young v. United Parcel Service, No. 12-1226, turns on the language of the pregnancy law. It requires employers to treat “women affected by pregnancy” the same as “other persons not so affected but similar in their ability or inability to work.”

There is no dispute that some UPS workers were offered accommodations. What the two sides disagree about is whether the law required Ms. Young to be treated the same way.

The company made accommodations for workers who were injured on the job, who were covered by the Americans With Disabilities Act and who lost their driving certification from the Department of Transportation.

“They even accommodated people who lost their regular driver’s licenses due to drunk-driving convictions,” said Sharon Fast Gustafson, one of Ms. Young’s lawyers. “They would give them a separate driver to drive the truck while they were delivering packages.”

The company countered that it had treated Ms. Young the same as “other employees with similar lifting restrictions resulting from an off-the-job injury or condition.”

That is slicing things too finely, said Samuel Bagenstos, a law professor at the University of Michigan who will argue in the Supreme Court on behalf of Ms. Young. “What went wrong here,” he said, “is that UPS did not treat Peggy Young as it did any other valued employee.”

Ms. Young, 42, left UPS in 2009 and now works for a government contractor. She has three children, and she said she would be thinking about them when the Supreme Court heard her case.

“I don’t want my daughters to have to choose,” Ms. Young said, “between having a baby and supporting a family.”