US President Donald Trump on Monday (23 January) signed a decree that bans government funding for American non-governmental organisations (NGOs) that support abortion abroad.
The move comes two days after millions of women, in Washington DC and across the globe, marched to defend their rights, including abortion.
Trump, an opponent of abortion, signed the directive at a ceremony in the White House three days after his inauguration.
Serra Sippel, president of the Center for Health and Gender Equity in Washington, told Reuters: "Women's health and rights are now one of the first casualties of the Trump administration.
"The global gag rule has been associated with an increase in unsafe abortions and we expect that Trump's global gag rule will cost women their lives."
The far-reaching gag rule affects groups getting funding from the US Agency for International Development, even if they use separate money for abortion services, counselling or referrals, advocates note.
The policy puts groups that provide women's health care in an "untenable position," said Brian Dixon of Population Connection Action Fund.
They can either accept the restriction to keep their funding or they can reject the restriction and lose their funding, Dixon said: "Either choice hurts the women that rely on them."
The law was initially created under President Ronald Reagan in 1984, but was revoked by President Bill Clinton when he took office in 1993.
President George W Bush then reinstated it in 2001 only for President Barack Obama to lift it again in 2009 when he took office.
"Life-saving global health funding should not be a political football," said Ann Starrs, head of the Guttmacher Institute, a leading reproductive rights group. There is no evidence the rule reduces abortion, she said.
"In fact, by targeting funding for overseas family planning programs, it may well have the opposite effect by making it harder for many women to avoid unintended pregnancy, which in turn would increase recourse to unsafe procedures by women who cannot access safe abortion care," Starrs added.