At the same time, Republicans on Capitol Hill are threatening to withdraw taxpayer funding for Planned Parenthood, the reproductive rights behemoth. The group is the lead financial sponsor of the Women’s March and is helping to organize the event, along with Naral Pro-Choice America and other abortion-rights organizations. Their participation makes it clear: Abortion opponents are out of step with the march.

“Reproductive freedom or reproductive justice means that women decide the fate of our own bodies,” Gloria Steinem, an honorary co-chairwoman of the march, wrote in an email message. She said if women “want to make decisions over their own bodies themselves, and want other women to have the same power, then they should feel very welcome at the march.”

Yet many women do not. Among them is Charmaine Yoest, a vocal opponent of abortion who is a senior fellow at American Values, a conservative organization here.

“This is what we conservative women live with all the time, this idea that we somehow aren’t really women and we just reflect internalized misogyny,” she said. Of the march, she added: “I don’t think they represent women. I think they are a wholly owned subsidiary of the abortion movement.”

The relationship, and sometimes tension, between reproductive rights and feminism goes back decades, to the inception of so-called second wave feminism in the 1960s; the first wave culminated in women winning the right to vote. Its pioneers, echoing the American left’s fight for racial justice and its opposition to the Vietnam War, embraced the birth control pill as a way to give women more power over their own lives. Thus a sexual revolution was born.

In 1973, just as middle-class women were abandoning homemaking for the work force, inspired by writers like Ms. Steinem and Betty Friedan, the Supreme Court handed down Roe v. Wade. That drove a wedge in the women’s movement, said Carole Joffe, a sociologist and reproductive rights advocate at the University of California, San Francisco.