Donald Trump's government has issued a ruling that allows employers to opt out of providing free birth control to millions of Americans.
The rule allows employers and insurers to decline to provide birth control if doing so violates their "religious beliefs" or "moral convictions".
Fifty-five million women benefited from the Obama-era rule, which made companies provide free birth control.
Before taking office, Mr Trump had pledged to eliminate that requirement.
The mandate requiring birth control coverage had been a key feature of so-called Obamacare - President Obama's efforts to overhaul the US healthcare system.
But the requirement included a provision that permitted religious institutions to forgo birth control coverage for their employees.
The Department of Health and Human Services (HHS) said on Friday it was important to expand which organisations can opt out and deny free contraceptive coverage.
"We should have space for organisations to live out their religious ideas and not face discrimination because of their religious ideas," said one HHS official, who did not wish to be named.
In January, tens of millions of women marched, making their voices heard. They will not stand for anti-women policies like this. 9/— Sen. Maggie Hassan (@SenatorHassan) October 6, 2017
Speaker of the House Paul Ryan, the top Republican in Congress, praised the decision as "a landmark day for religious liberty".
The American Civil Liberties Union (ACLU) and the National National Women's Law Center have announced that they will sue the federal government over the decision.
Why was the decision made?
In announcing the rule change, HHS officials cited a study claiming that access to contraception encourages "risky sexual behaviour".
The department disputes reports that millions of women may lose their birth control coverage if they are unable to pay for it themselves.
Roger Severino, the director of the HHS Office of Civil Rights, argued that only a small percentage of employers will choose to opt out, and therefore only a limited number of women will be affected.
But many health policy analysts say employers that do not wish to pay for their employees' contraceptive coverage will now be able to.
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Diedra from Washington state told the BBC she feared losing access to the birth control she uses to treat polycystic ovarian syndrome. At the moment, the treatment is paid for with partial subsidies through the Affordable Care Act.
"Without the birth control mandate I don't know how much the treatment would cost," she said.
"This is definitely an attack on women - if this issue affected men it wouldn't be happening this way."
How have women's groups reacted?
By Nada Tawfik, BBC News, New York
The immediate outcry from the president's detractors has been that this is an attack on women.
Birth control is used for a variety of reasons. Preventing unwanted pregnancy is, of course, one of them. But it can also be used to treat medical conditions such as endometriosis or polycystic ovarian syndrome.
The American Congress of Obstetricians and Gynecologists was blunt. They said the decision undermined the best interests of their patients and turned back the clock on women's health.
Another women's advocacy organisation, UltraViolet, said employers and insurers now needed to pick a side, asking if they stood "with Donald Trump and his attacks on women," or "the women who depend on your coverage?"
The administration says only a limited number of women will be affected.
Whether or not that is true, the president is being criticized for politicising women's bodies and health to score political points with his base.
Is there a political price to pay?
By Anthony Zurcher, BBC News, Washington
The contraceptive coverage mandate had become a hotly contested legal battleground since Obamacare passed in 2009 - with the Democratic administration aggressively pushing back against attempts to carve out sweeping religious exemptions to the women's health provisions of the law.
With Donald Trump now in charge, the dynamic has been turned on its head. Now the White House will be much more lenient in granting waivers, and Obamacare's defenders are the ones turning to the courts for a remedy.
The move will be celebrated by religious groups and conservatives - a tangible benefit of their presidential victory last year.
There's a risk of blowback outside the Republican Party's evangelical base, however.
According to some estimates, the contraceptive mandate saved women $1.4bn in its first year in effect. The decision could deal a direct financial blow to women across the US - something they might remember when they head to the polls in 2018.
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