Iowa Gov. Kim Reynolds on Friday signed a law banning most abortions if a fetal heartbeat can be detected, or at around six weeks of pregnancy, marking the strictest abortion regulation in the nation — but setting the state up for a lengthy court fight.

The Republican governor signed the legislation in her formal office at the state Capitol as protesters gathered outside chanting, "My body, my choice!" Reynolds acknowledged that the new law would likely face litigation that could put it on hold, but said: "This is bigger than just a law, this is about life, and I'm not going to back down."

Reynolds signed the law surrounded by children from a local Christian school and children related to supporters.

The ban, set to take effect on July 1, has moved Iowa to the front of a push among conservative statehouses jockeying to enact new restrictions on the medical procedure. Mississippi enacted a law earlier this year banning abortions after 15 weeks of pregnancy, but it's on hold after a court challenge.

The Iowa law provides exemptions for abortions during a later pregnancy stage to save a pregnant woman's life or in some cases of rape and incest. A woman would have to report a rape within 45 days to law enforcement or a physician, and incest would need to be reported within 140 days. Another provision prohibits some uses of fetal tissue, with exemptions for research.

Maggie DeWitte, who leads the group Iowans for Life, called Reynolds' move "historic" and added: "She is following through on her pledge to the people of Iowa that she is 100 percent pro-life."

The bill signing came shortly after the Iowa affiliates of Planned Parenthood and the American Civil Liberties Union warned that they would sue the governor if she signed the bill, which the Republican-controlled Legislature approved during after-hours votes earlier in the week.

"We will challenge this law with absolutely everything we have on behalf of our patients because Iowa will not go back," Suzanna de Baca, president and CEO of Planned Parenthood of the Heartland, said in a statement.

Backers of the so-called heartbeat bill — which didn't get a single Democratic vote in the Legislature during final passage and included no votes by six Republicans — expressed hope it could challenge Roe vs. Wade, the landmark 1973 U.S. Supreme Court ruling that established women have a right to terminate pregnancies until a fetus is viable.

A federal appeals court in recent years has struck down similar legislation approved in Arkansas and North Dakota, but conservatives say an influx of right-leaning judicial appointments under President Donald Trump could produce a different outcome in the future.

"This just all propels the whole movement to protect life forward," Republican Rep. Sandy Salmon said after the signing.

Critics argued the bill would ban abortions before some women even know they're pregnant. Outside of Reynolds' office earlier Friday, critics of the bill began leaving coat hangers by her staff's desks. A morning rally outside of the Capitol included more than 100 people who held signs in opposition to the legislation.

Jessi Allard, a 35-year-old youth counselor at a Des Moines shelter, held a sign outside Reynolds' office that read: "You don't own us." Allard said lawmakers need to support social services that help children beyond birth and into adulthood. She called the legislation disappointing.

"It's ridiculous that our government can govern women's bodies," she said.

The same Republican-majority Legislature in Iowa passed a 20-week abortion ban last year. It's now in effect, though a provision requiring a three-day waiting period to get an abortion is tied up in a lawsuit filed by Planned Parenthood and the ACLU. Separately, Republican lawmakers agreed last session to give up millions in federal dollars to create a state-funded family planning program that excludes abortion providers like Planned Parenthood, even though the money wasn't going toward abortions.