Millions of American women are receiving birth control at no cost to them through workplace health plans, the result of the Obama-era Affordable Care Act, which expanded access to contraception.

The Trump administration sought to allow more employers to opt out because of religious or moral objections. But its plans were put on hold by two federal judges, one in Pennsylvania and the other in California, in cases that could eventually reach the Supreme Court.

The judges blocked the Trump policy from going into effect while legal challenges from state attorneys general continue.

Here's a look at some of the issues behind the confrontation over birth control, politics and religious beliefs:

Well into the 1990s many states did not require health insurance plans to cover birth control for women.

"Plans were covering Viagra, and they weren't covering birth control," said Alina Salganicoff, director of women's health policy with the nonpartisan Kaiser Family Foundation.

By the time President Barack Obama's health law passed in 2010, employers and insurers largely began covering birth control as an important part of health care for women.

The ACA took that a couple of steps further. It required most insurance plans to cover a broad range of preventive services, including vaccinations and cancer screenings, but also women's health services. And it also required such preventive services to be offered at no charge.

Employers and insurers were required to cover at least one of each class of birth control approved by the Food and Drug Administration. That included costly long-acting contraceptives, generally more effective than birth control pills.

It's estimated that 55 million to more than 62 million women now receive birth control at no cost, with only a small share paying for contraception.

"The irony I find about this battle is that in the period of time this policy has been in effect, teen pregnancies have gone way down and the number of abortions has gone way down," said Kathleen Sebelius, Health and Human Services secretary under Obama.

While those rates were already going down before the health law, the trend does continue.