For the first time in more than 30 years, the U.S. Equal Employment Opportunity Commission (EEOC) issued guidance on Monday clarifying the terms of the federal pregnancy discrimination law, emphasizing that employers must offer their pregnant employees reasonable accommodation if they’re temporarily unable to do their jobs.

The commission, which last published guidelines on pregnancy discrimination laws in 1983, spelled out the ways employers must adhere to the Pregnancy Discrimination Act in the face of continual violations of the law and a public hearing about the issue in 2012.

The Pregnancy Discrimination Act was passed in 1978 as an amendment to the Civil Rights Act of 1964 for companies with at least 15 employees. Under the new guidelines, the law covers discrimination not only for current pregnancies but for past and future pregnancies, too. Lactation and breast-feeding are considered medical conditions related to pregnancy and are also protected by the law.

Employers also can’t force pregnant workers to take leave if they’re still able to work, and they have to provide the same parental leave policies to men as they do to women, though that’s considered separate from the medical leave that comes along with giving birth or recovering from childbirth, the guidelines said.

And finally, the EEOC sought to clarify when employers have to provide accommodation for their workers who have impairments related to pregnancy, such as gestational diabetes or preeclampsia.

“Too many courts have read the 1978 law inappropriately narrowly,” said Emily Martin, vice president and general counsel at the National Women’s Law Center (NWLC). The EEOC’s new guidance “talks about all of the key areas where we continue to see pregnancy discrimination,” she said. “I think the real question now is if courts listen to it.”

The 1978 law forbade employment discrimination against women on the basis of pregnancy or conditions related to it, and called for employers to treat pregnant workers the same as they would an employee with a similar limitation.

But what happened in practice, say experts, is that employers would agree to accommodate a pregnant worker’s temporary disability — say, she was unable to lift heavy objects — by forcing her to take unpaid leave. In other cases, companies have fired women for taking out time to breast-feed on the job, or demoted them because they planned to get pregnant in the future.

In other words, the initial intent of the Pregnancy Discrimination Act “has not really come through for a lot of employers,” according to Peggy Mastroianni, who serves as a legal counsel at the EEOC.

While she says the number of pregnancy discrimination complaints received by the EEOC hasn’t increased every single year, it has steadily risen in recent decades — from 3,977 filed in 1997 to 5,797 in 2011, a 46 percent increase.

“These charges, too many of them are meritorious,” Mastroianni said of the increasing number of pregnancy discrimination claims filed. “I know it sounds weird to say that. So many of them involve incredibly blatant discrimination.”

Among the more egregious examples of now-settled complaints, she said, involved — ironically — a maternity clothing chain that in 2007 fired a saleswoman when she got pregnant.

In another case, a sports bar didn’t allow pregnant employees to work on Sundays because “men didn’t want to see pregnant women” while they watched football.

In still another example, a woman was fired from her job when she asked her employer whether she’d be able to pump breast milk after returning to work from maternity leave. A federal trial court had dismissed the woman’s sex discrimination suit on the grounds that "lactation is not pregnancy, childbirth, or a related medical condition," but the U.S. Court of Appeals for the Fifth Circuit ruled that her firing constituted sex discrimination under the Pregnancy Discrimination Act.

The rise in complaints may be attributed to the burgeoning presence of women participating in the workforce and their increasing status as household breadwinners in American families, the EEOC said. They’re also increasingly working longer into their pregnancies, and having children, on average, at an older age, which means that they’re more likely to have work experience under their belt.

But the persistence of pregnancy discrimination cases is also a result of enduring stereotypes about women's abilities in the workplace, say experts.

“Those stereotypes harm women in a variety of ways, including when an employer believes a woman intends to have children, which can negatively impact how an employer perceives her competence as a worker,” said the NWLC’s Martin.

The EEOC stressed that the newly released guidelines have been in the works for years, and are not a response to the case of Young vs. UPS, which the U.S. Supreme Court recently agreed to hear.

In that case, which Martin calls “the perfect example of how the courts have gotten it wrong,” Peggy Young, a Maryland-based UPS employee, sued the company after it denied her a light duty assignment when her doctor told her she shouldn’t lift heavy objects. She said UPS told her it made that allowance only for workers with job-related injuries or those who are permanently disabled under the Americans With Disabilities Act.

The Pregnancy Discrimination Act calls for employers to offer the same accommodation for pregnant employees as those offered to non-pregnant employees "similar in their ability or inability to work."

But the U.S. Court of Appeals for the Fourth Circuit ruled in favor of UPS (PDF).

In 2008, the U.S. government expanded the definition of the Americans With Disabilities Act of 1990 to include disabilities that are “episodic” in nature.

The EEOC’s new guidelines clarify that pregnancy-related impairments are covered under that disability expansion, as well as under the pregnancy discrimination law, according to Ariela Migdal, a senior staff attorney with the ACLU’s Women’s Rights Project.

“It means that they’re entitled under that law to a reasonable accommodation because of an impairment related to pregnancy,” she said. “They have protection from both statutes.”