For those of us still sitting shiva for abortion clinic buffer zones and the contraceptive coverage mandate, it might feel too soon to point out the brand new landmines awaiting women in the Supreme Court’s current term. But on Wednesday, the court will hear arguments in another case involving the reproductive lives of America’s female workers—this one interpreting the scope of the federal Pregnancy Discrimination Act, or PDA. Given this court’s track record, advocates for gender equality—sorry, Justice Alito, no quotation marks for me—are hoping for the best but preparing for the worst.

The case, Young v. UPS, comes from the 4th Circuit Court of Appeals and concerns Peggy Young, who worked as a driver for the courier service in Landover, Maryland. Young became pregnant in 2006 and was instructed by her medical provider, as many pregnant women are, to avoid lifting more than 20 pounds. Young rarely had to deliver packages that heavy, but UPS refused to excuse her from those duties, or to reassign her for the remainder of her pregnancy to a “light duty” job. UPS had a policy allowing such temporary reassignments but limited them to three circumstances, none of which applied to pregnancy: when a worker’s impairment was due to an on-the-job injury, qualified her for “reasonable accommodation” under the Americans With Disabilities Act (which typically does not include a “normal” pregnancy), or had caused her to lose her commercial driver’s license.

Unwilling to disregard her doctor’s directive, Young had to go on unpaid leave. At that point, she was just 14 weeks pregnant. She ultimately went without pay for six months and lost her medical coverage before having her baby because she didn’t work the number of hours UPS required to maintain those benefits.

Young’s story is increasingly typical. Women now constitute close to half the workforce, and three-quarters of them will be pregnant at least once during their working lives. Most pregnant women stay on the job right up until their due dates; according to a U.S. Census Bureau study, in the past 50 years, the number of women working into their ninth month more than doubled, with a whopping 82 percent of women who gave birth between 2006 and 2008 working into their final month of pregnancy. Coupled with these demographic realities are pregnancy’s medical realities: Even an uncomplicated pregnancy can cause nausea, migraines, urinary tract infections, carpal tunnel syndrome, back pain, shortness of breath, dizziness, and chronic fatigue while more serious conditions include diabetes, deep vein thrombosis, placenta previa, and pre-eclampsia. For women in jobs that involve prolonged standing (retail clerks, cashiers), are physically strenuous or dangerous (firefighters, law enforcement officers), or include contact with toxic materials (janitors, hotel housekeepers), pregnancy can be in direct conflict with their ability to work. Simply put, in order to continue earning a paycheck while pregnant, many women will need their employers to make some adjustments.

Many, like UPS, resist doing so. Some of these employers are household names (Walmart, Pier One, Old Navy, Kroger), and others you’ve probably never heard of (Fierman Produce Exchange, Unique Thrift, the city of Florence, Kentucky). A joint report published in 2013 by the National Women’s Law Center and A Better Balance noted that even seemingly easy fixes, like allowing a woman to carry a water bottle or to sit down periodically, have been denied time and again. Indeed, a recent study by the National Partnership for Women & Families estimates that more than 250,000 women a year have their accommodation requests denied. These women are left with the Hobson’s choice of risking their pregnancies or losing their jobs. While Young was lucky enough to keep hers—after her three months of Family and Medical Leave Act leave ran out, she was allowed to take an extended leave of absence, albeit unpaid, under the terms of her union contract—countless others are simply fired for absenteeism. In either case, for an expectant mother to lose a paycheck just as she’s about to have another mouth to feed is a devastating outcome.

This has been going on for years. What’s new is that women are increasingly turning to the courts, accounting in part for an explosion of pregnancy discrimination charges filed with the Equal Employment Opportunity Commission, the federal agency that enforces the PDA, and its state counterparts. Charges filed with those agencies increased by nearly 50 percent between 1997 and 2011, and recent statistics confirm that women in low-wage and “nontraditional” jobs are filing most of those claims.

Under the PDA, employers are required to treat pregnant women the same as workers who are “similar in their ability or inability to work.” Young argued that because UPS accommodated workers with physical limitations other than pregnancy—that is, it granted light duty to workers who were “similar” to Young in their “inability” to perform all job functions—then it violated the PDA by refusing to grant the same to her. But the trial judge dismissed Young’s case and the 4th Circuit Court of Appeals upheld that dismissal, for two reasons. First, because UPS’s policy didn’t specifically state a bias against pregnant workers, then it wasn’t deemed discriminatory. And second, the court reasoned that Young actually wasn’t “similar” to any of those three categories of workers to whom UPS granted accommodation, so she wasn’t entitled to be treated the same as they were.

The first rationale has been followed by a number of other courts, and is patently wrong. To explain why requires a brief detour into the history of why the PDA was passed in the first place. Congress enacted the law in 1978 as a direct rebuke to a recent Supreme Court decision finding that General Electric’s policy of excluding pregnancy benefits from its employees’ disability plan did not discriminate against women, even though only women can get pregnant so only women were harmed by the policy.* In the court’s memorable words, a distinction between pregnant women and “non-pregnant persons” was a distinction based on a particular medical condition, not gender. Voilà—no sex discrimination.

It was precisely this specious distinction that Congress rejected in passing the PDA two years later. It recognized that when a pregnant employee is denied benefits granted to other employees, it’s sex discrimination, even in the absence of a stated bias against pregnant workers.

The 4th Circuit’s second rationale—that Peggy Young was not entitled to a light duty assignment because she was not “similar” to others who did get them—exposes a fundamental limitation in the PDA as currently written: A pregnant worker gets an accommodation only if other employees with comparable impairments get them, too. The 4th Circuit and other courts have ignored the statute’s built-in definition of who’s comparable—those “similar in their ability or inability to work”—instead requiring that the other employees be similar to the pregnant worker in all respects. So a worker who is accommodated because of an on-the-job injury, or an ADA-qualifying disability, or a lost commercial driver’s license, is not “similar” to a pregnant worker. Thus, the pregnant worker can’t seek the same accommodation.

Without a court remedy, retooling the PDA itself is another strategy: The Pregnant Workers Fairness Act has been introduced each year in Congress since 2012 and would establish an independent right of accommodation for pregnancy—that is, a right that doesn’t tether pregnant workers’ fates to their co-workers’. Nine states and some municipalities already have some version of the PWFA, but those laws assist a fraction of the women who need their protections.

Whatever the outcome in Young, clarity can’t come soon enough. UPS did its part to muddy the waters by announcing in its Supreme Court brief, filed in late October, that it had changed its accommodation policy to include pregnancy, though that backtracking comes too late to help Young. (UPS claims it made the change not because the PDA requires it but just to make the company’s life easier as it becomes subject to the patchwork of new state and local accommodation laws.) Meanwhile, even employers who purport to want to do the right thing get it wrong. For instance, after pressure from a coalition of female employees, female shareholders, and women’s rights groups, including the filing of a class-action complaint with the EEOC, Walmart announced in the spring that it was changing its policy regarding pregnancy accommodation. But while the company abandoned its Young-like position that pregnant women never are entitled to the same modifications as ADA-protected workers, its new policy only applies to those pregnant women deemed “disabled”—a definition that’s left up to Walmart to determine in each case. It’s far from certain whether someone like Peggy Young, who sought relief from heavy lifting to preserve a healthy pregnancy, would qualify; both advocates and Walmart employees are agitating for the company to revise the policy further.

Meanwhile, the chorus supporting Peggy Young is getting louder. In July, the EEOC issued a new “enforcement guidance” on pregnancy discrimination that roundly criticized the Young court and its ilk as misconstruing the PDA. It also joined a “friend of the court” brief submitted by the federal government in Young urging reversal of the 4th Circuit’s ruling. A number of prominent women’s groups have filed similar briefs, as have federal, state, and local legislators, law professors, female business leaders, labor unions, and even a coalition of anti-abortion organizations (who contend, accurately, that without on-the-job accommodation, some desperate women will have abortions so that they can keep working).

Of course, when it comes to this Supreme Court’s take on women, pregnancy, and employment rights, there is good reason to think its decision in Young will only make things worse. But, as illustrated by the infamous Lilly Ledbetter pay discrimination decision in 2007—which prompted a swift rebuttal from Congress in the form of the Lilly Ledbetter Fair Pay Act—not to mention the PDA itself, enacted to nullify the General Electric ruling, sometimes lawmakers’ best motivation comes from a disaster in the judiciary. If the court upholds the 4th Circuit’s narrow, wrongheaded reading of the PDA, the Pregnant Workers Fairness Act might finally get traction.

Regardless of whether resolution comes from the court or Congress, it’s about time that we acknowledge that pregnancy is a major medical event for working women, and some women’s job duties may conflict with pregnancy’s physical effects. Without some collective commitment to making the temporary accommodations necessary for those women to continue working safely, then we’re committing to a future full of Peggy Youngs—women whose pregnancies cost them their paychecks.

*Correction, Dec. 3, 2014: This article originally misstated that General Electric once had a policy of excluding pregnancy benefits from its employees’ medical plans. It was not their medical plans, but their disability plans. (Return.)