New laws in Arkansas and Arizona require doctors to inform women that drug-induced abortions can be “reversed” mid-procedure, a claim that quickly drew charges of “junk science” from abortion-rights groups and many doctors.

The Arkansas law took effect late Monday, after Gov. Asa Hutchinson (R) signed it. Arizona Gov. Doug Ducey (R) signed his state’s bill into law earlier this month.

Supporters say the measures require providers to give women information that could prove critical if they have a change of heart.

“No medical reason exists to deny mothers the opportunity to choose life by sharing with them all their options,” Charmaine Yoest, president of Americans United for Life, said in a statement. The group developed the model legislation that formed the basis for laws in both states.

But the American College of Obstetrics and Gynecology (ACOG) was among those arguing against the measures, saying claims of “reversal” are unsupported by medical evidence.

“Claims of medication abortion reversal are not supported by the body of scientific evidence, and this approach is not recommended in ACOG’s clinical guidance on medication abortion,” says an ACOG fact sheet on the Arizona law.

The laws are part of a wave of state legislation aimed at reducing access to abortion rather than banning it outright. Also on Tuesday, Kansas Gov. Sam Brownback (R) signed a bill banning those second-trimester abortion procedures known in medical circles as “dilation and evacuation” in which fetal death is caused by dismemberment with forceps or other instruments.

The pharmaceutical abortions targeted in Arkansas and Arizona occur much earlier in a woman’s pregnancy — typically in the first trimester. In the United States, such abortions typically occur in two steps.

First, the woman is given mifepristone, once known as RU-486, which can terminate very early pregnancies and dilate the cervix. A few days later, the second drug, misoprostol, induces contractions to expel the embryo.

In an op-ed in the National Review, Mailee R. Smith, staff counsel for Americans United for Life, argues that a heavy dose of progesterone can block the effects of the first drug, permitting the pregnancy to continue normally.

“At this point, it has been reported that 80 babies have been born following the abortion-reversal process, with another 60 or so on the way (still in utero),” Smith wrote.

ACOG, however, says “scant evidence” supports the claim that progesterone can halt an abortion, and that a woman who changes her mind mid-abortion is better off simply not taking the second drug.

“In 30 percent to 50 percent of women who take mifepristone alone,” the fact sheet says, “the pregnancy will continue.”

The group has joined abortion-rights advocates in criticizing legislation that requires doctors to convey medical advice to their patients, particularly when that advice is unproven.

“Extreme legislators are so focused on preventing a woman from getting an abortion that they are willing to ignore the medical experts and hide behind junk science,” Jennifer Dalven, director of the American Civil Liberties Union’s Reproductive Freedom Project, said in a statement.

Correction: An earlier version of this story incorrectly reported that Arkansas Gov. Asa Hutchinson did not sign that state’s bill. He did sign it, and the story has been corrected. An earlier version of the story also mischaracterized the new Kansas law as banning all “dilation and evacuation” abortions in the second trimester. The law does not ban all such procedures, only ones in which fetal death is caused by dismemberment with forceps or other instruments. That has also been corrected.