Just days into his presidency,Trump has already barried US federal funding of foreign NGOs that support abortion.
The annual "March for Life" takes place six days after millions rallied in progressive women-led protests in cities across the United States and around the world to warn President Donald Trump that they will not stand for attacks on their freedoms -- including access to abortion.
The 44th edition of the march, which bills itself as the world's biggest "pro-life" rally, also expects to draw participants from all corners of the country, exactly one week after Trump's inauguration.
"A lot of people are expecting it to be the largest March for Life in a long time," said Chris Gast, the communications director for Right to Life of Michigan.
The city of Grand Rapids alone is sending 12 bus loads of people to Washington, he said.
The march will also take place days after the 44th anniversary of Roe v. Wade, the landmark US Supreme Court decision that legalised abortion in 1973.
Just days into his presidency, Trump has already taken actions cheered by abortion foes -- on Monday, he signed a decree barring US federal funding for foreign NGOs that support abortion.
And next Thursday he will announce his choice to fill an empty spot on the Supreme Court, with the nominated justice widely expected to be anti-abortion.
The March for Life and last week's Women's March share the same venue: the National Mall in Washington, a huge lawn lined with museums and memorials in the heart of the US capital.
Friday's march is not officially political and doesn't only attract Trump supporters, but the featured speakers include three Republican lawmakers and Kellyanne Conway, an influential senior aide to the president.
Coming from a Catholic background, the mother of four will share the stage with Cardinal Timothy Dolan of New York and other religious leaders.
The march will begin south of the White House, head east alongside the Mall and end at Capitol Hill, where Republicans have the majority in both legislative chambers.
But the focus of the marchers will be on the building opposite the Capitol: the US Supreme Court, which has the final say on abortion, a constant topic of passionate debate in the country.
March for Life participants know that if Trump is in a position to appoint a second conservative Supreme Court justice during his White House tenure, their dream of overturning Roe v. Wade could become reality.
About seven out of 10 Americans, however, are opposed to tossing out the 1973 high court decision that established a woman's right to have an abortion in the first three months of pregnancy, according to a study by the Pew Research Center this month.
While waiting for the day that abortion is outlawed in the United States, opponents are leading the charge against the practice at the state and local level, encouraged by the ascension of anti-abortion heavyweights like Vice President Mike Pence and Trump's nominee for attorney general, Jeff Sessions.
According to the Guttmacher Institute, a research organization that supports abortion rights, US states enacted 338 restrictions on abortion between 2010 and 2016.
Pro-choice advocates who support the right of women to have access to contraception and abortions are particularly anxious about Trump's health secretary nominee Tom Price, who as a congressman consistently voted to block access and funding for abortion.
"This looming federal onslaught against a broad spectrum of reproductive health services threatens a massive rollback of women's health, rights and autonomy," the Guttmacher Institute said.