Starting Tuesday, millions of U.S. workers will gain vastly expanded protections under a new law that bars employers from discriminating against pregnant women and requires companies to provide accommodations so they can keep doing their jobs while they're expecting. 

The Pregnant Workers Fairness Act, aimed at promoting women's health and economic well-being, effectively protects pregnant women from having to choose between their paychecks and their health, according to experts. 

"The PWFA is the culmination of a 10 year-long campaign to close gaps in civil rights laws so pregnant workers are not pushed out of jobs or forced to risk their health when they require reasonable accommodations on the job, like a water bottle to stay hydrated or a transfer away from strenuous heavy lifting," Elizabeth Gedmark of A Better Balance, an advocacy group for pregnant workers, told CBS MoneyWatch.

Falling through the cracks

The new law effectively patches a legal gap between the Americans with Disabilities Act (ADA) and the Pregnancy Discrimination Act (PDA) in which pregnant women could fall through the cracks in the workplace.

"We have heard from workers who say they were put in that impossible position of choosing between a paycheck and a healthy pregnancy," Gedmark said. 

The ADA, in place since 1990, prohibits employers from discriminating against employees with disabilities and also requires that they make accommodations for them. However, under the ADA, pregnancy itself is not considered a disability that requires accommodation. 

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The PDA, enacted in 1978, bans employers from discriminating on the basis of pregnancy in hiring and firing. For example, the act makes it illegal for an airline to push out a flight attendant once she becomes visibly pregnant. 

However, it only allows pregnant workers to be treated as well as, or equal to, another worker. That means an employee who is expecting could be tasked with physically grueling work.

"The problem for physically demanding workplaces was it can be difficult to identify someone else being treated the way you need to be treated," Gedmark said. "Employers can treat everyone poorly and someone would then have to risk their health."

Neither law offers protections for otherwise healthy pregnant workers with pregnancy-related limitations. But under the law taking effect on Tuesday, employers must provide reasonable accommodations for known limitations related to pregnancy, unless doing so would pose an undue burden or hardship on a business' operations.

"Because pregnancy is temporary, that hardship standard is harder," Christine Bestor Townsend, an employment attorney with Ogletree Deakins, told CBS MoneyWatch. "If I have to accommodate something for six months, that's different from accommodating it for five years or the rest of time." 

What it means for workers

With the Pregnant Workers Fairness Act, employers must now consider giving pregnant workers a range of accommodations such as access to water, closer parking, flexible hours and additional bathrooms breaks.

Employers must also discuss such allowances with a pregnant worker and may not force an employee to take leave if an accommodation would allow them to remain productive on the job.

"Employees don't have to use any magic language. Employers need to recognize the requests that come in and be prepared to deal with those requests," Bestor Townsend said.

Pregnant workers have long asked for pregnancy-related accommodations, and some states already have laws in place that mirror the act. 

"The PWFA just gives another vehicle for employees to have additional rights in the workplace," Bestor Townsend said.

Physicians recommend that pregnant women avoid or limit certain tasks, including exposure to chemicals, lifting heavy loads, working overnight or extended shifts, and sitting or standing for prolonged periods of time. Such activities can increase the risk of miscarriage, premature birth, low birth weight, urinary tract infections and fainting, according to health experts.

The House Committee on Education and Labor offered examples of reasonable accommodations in its report on the PWFA. They include providing pregnant workers with seating; water; closer parking; flexible hours; appropriately sized uniforms and safety apparel; additional bathroom, meal and rest breaks; and relief from strenuous activities as well as work that involves exposure to compounds unsafe for pregnancy.

In practice, the new law will allow the three-quarters of women who will be pregnant at some point in their careers to maintain those careers. Women increasingly support their families, with 41% of mothers identifying as the sole or primary breadwinners in their households, according to the report. 

"What it means is millions of women who want to keep working, who need to keep working to feed their children [and] pay their rent will be able to," ACLU senior legislative counsel Vania Leveille told CBS MoneyWatch. "It means they can go to their employer and say: 'I'm pregnant and I want to keep working, I can keep working, but I need this little modification.' The employer can no longer say, 'Too bad, you're fired' or 'You have to go on unpaid leave' or 'We don't have to discuss this.'"