North Dakota became the latest state on Monday to enact a near-total ban on abortion, just one month after the State Supreme Court temporarily blocked a similar ban from taking effect.

Under the new law, an abortion in the case of rape or incest would be permissible only in the first six weeks of pregnancy, a time when most women have not yet realized they are pregnant. Abortion is permitted without gestational limits if terminating a pregnancy can “prevent the death or a serious health risk” of the mother.

Gov. Doug Burgum, a Republican, signed the bill into law on Monday.

The law, Mr. Burgum said, “reaffirms North Dakota as a pro-life state.” The governor added that it also “clarifies and refines” the existing state ban that has been blocked by courts.

The new law, which takes immediate effect, is a dramatic shift for the state, where abortions had been legal up until 22 weeks of pregnancy.

Under the earlier ban, providers who performed an abortion to save the life of a mother could face felony prosecution. The provider would need to offer an “affirmative defense” proving that the abortion was medically necessary within the confines of the state law.

Under the new version of the law, the exceptions do not require an affirmative defense from providers. But providers could still face criminal charges if they violate the exceptions detailed in the law.

The law makes North Dakota at least the 14th state with an active ban on nearly all abortions, though it is likely to face legal challenges, experts said.

Since the U.S. Supreme Court overturned the constitutional right to abortion last year, conservative states have enacted restrictions or full bans. Liberal states have gone in the opposite direction, reaffirming abortion rights in state constitutions and becoming magnets for women seeking abortions in states with bans.

North Dakota’s trigger ban was blocked last year by a district judge, after its sole abortion provider, the Red River Women’s Clinic, filed a lawsuit against the law.

The State Supreme Court upheld the lower court’s ruling last month and said the state Constitution protected abortion rights in some situations.

“North Dakota lawmakers are attempting to bypass the state Constitution and court system with this total ban,” said Elisabeth Smith, director of state policy and advocacy at the Center for Reproductive Rights, which brought the lawsuit on behalf of Red River clinic. “They made the exceptions a little bit less narrow but essentially tried to repackage the trigger ban.”

Ms. Smith said the center was still analyzing the new law and had not “determined what the next steps will be.”

Tammi Kromenaker, director of the Red River clinic, called the new law “an assault on bodily autonomy and abortion rights.”

“This legislation is out of step with the people of North Dakota,” Ms. Kromenaker said.

The Red River Women’s Clinic stopped offering abortions in the state, instead moving a short drive across the border to Moorhead, Minn., in August. But attorneys representing the clinic say it is important to ensure that the ban does not take effect, so that patients facing medical emergencies can receive abortions in hospitals and from their doctors.

“North Dakota has been pro-life before statehood, and before Roe,” said the bill’s sponsor, Senator Janne Myrdal, a Republican. “I’m passionate about protecting women, but also their unborn children, that goes hand in hand.”

Most states with sweeping abortion restrictions offer some exceptions to save the life of a mother, but translating those exceptions has sown confusion and turmoil among doctors and patients. In the months since the overturning of Roe v. Wade, very few exceptions to these new abortion bans have been granted, a New York Times review of available state data and interviews with dozens of physicians, advocates and lawmakers revealed.

In last month’s opinion, the North Dakota Supreme Court raised concerns that a sweeping abortion ban might violate “a fundamental right to an abortion in the limited instances of lifesaving and health-preserving circumstances.”

Amy Schoenfeld Walker contributed reporting.