Four states have laws on the books requiring doctors to tell people who want abortions that the procedure can be reversed. Another eight have introduced bills this year that would do the same.

There’s just one problem: There’s no conclusive evidence that the treatment behind the so-called “abortion reversal” works.

In theory, an “abortion reversal” works like this: In a medication abortion, a woman ends her pregnancy by taking two pills, mifepristone and misoprostol, several hours apart. If a woman changes her mind, however, after taking the mifepristone — which works to block progesterone, a hormone that helps sustain pregnancy — proponents of abortion reversal say that she can take repeated doses of progesterone to reverse its effects.

Such a regimen is probably safe. But critics say it remains unproven, and testing it out on patients just isn’t good medicine. Still, in Arkansas, Idaho, South Dakota, and Virginia, doctors are required by law to advise women that it’s an option if they change their mind about wanting an abortion.

“The tragedy, in a lot of this, is when legislators get involved in things that aren’t proven and then legislate requirements that impede care or are basically, potentially, lies,” said Mitchell Creinin, a professor at the University of California, Davis. “Without good science, we never know if something’s real or not. I mean, you wouldn’t want your doctor to tell you to take an aspirin to treat your cancer.”

Politics, meet science

Now, Creinin says he’s about to find out whether abortion reversal is, indeed, real. Thanks to a recent grant of more than $400,000 from the Society of Family Planning, which supports abortion and contraception research, Creinin is currently spearheading what’s thought to be the first study on abortion reversal that uses randomized, double-blind testing and placebos — all hallmarks of the most rigorous forms of studies. It’s been approved by UC Davis’ institutional review board, and registered with ClinicalTrials.gov.

The progesterone protocol is not recommended by the American Congress of Obstetricians and Gynecologists, which says any claims about abortion reversal’s effectiveness “are not based on science and do not meet clinical standards.”

Even Creinin, who plans to spend a year on his study, doesn’t think it’s possible. “It just doesn’t make any physiological sense,” he said.

Mifepristone helps end pregnancies because it binds tightly to the hormone receptors that also attach to progesterone, he explained, and no amount of progesterone can unwind those bonds. “If you have four bolts on your door, if you think that coming with some extra keys is gonna help you unlock the bolts when none of the keys necessarily work in the lock, it ain’t gonna open the door,” he said.

But mifepristone doesn’t always work — when taken alone, it’s commonly cited as ending just between 10 and 50 percent of pregnancies. Generally, if a woman changes her mind about having a medication abortion, doctors will advise her to simply not take the second pill.

Creinin is now recruiting 40 women, who must already want surgical abortions, to undergo his study. About two weeks before their planned abortion, study participants will first take mifepristone and then either progesterone or a placebo. They’ll be monitored until they get their surgical abortion, which the women must still pay for themselves.

“If there’s a difference between the groups and it shows that the group with the progesterone continued the pregnancy more and the group with the placebo lost the pregnancy more, then that shows the progesterone does something,” Creinin explained. He’s already started enrolling patients.

A new idea, championed by states

The idea that medication abortions can be reversed has been championed for years by California doctor George Delgado, who was the first to propose using progesterone to halt them.

While Delgado agrees that there should be more medical research into what he calls “abortion pill reversal,” he has concerns about Crienin’s approach. “He’s right: None of the studies that we’ve published have been prospective, randomized controlled trials, so that is a weakness, absolutely,” Delgado said.

But he’s worried that Creinin will use a less-effective progesterone regimen and that his study’s sample size is too small. (Creinin says that if Delgado is right about how effective the progesterone regimen is, Creinin will have enough participants to prove whether it works.)

Delgado told VICE News that he’s designing his own randomized controlled study and it will tentatively include 900 women. Each patient will be given one of three treatments involving progesterone; none will receive a placebo, as Delgado, who opposes abortion, considers that to be unethical.

He anticipates having results within two years.

Delgado first published a paper that claimed that progesterone could be used to reverse a medication abortion in 2012. That paper focused on just seven patients, four of whom ended up carrying their pregnancies to term without neonatal complications or birth defects. (One patient was lost to follow-up.) Delgado concluded that his progesterone regimen likely had a success rate of 66 percent. In April 2018, Delgado published a second, much larger paper. Out of 547 women who underwent a progesterone regimen shortly after taking mifepristone and who were followed throughout the study, 257 gave birth to live children.

Many researchers remained unconvinced that Delgado’s work was credible. In an article published in the New England Journal of Medicine, researchers pointed out multiple flaws in the second paper, including that some providers had excluded women whose pregnancies had already effectively ended by the time they decided to undergo the progesterone protocol — a move that potentially inflated its success rate.

“It is poorly designed and falls far short of providing sufficient evidence to recommend this course of treatment,” Hal Lawrence, a doctor and ACOG’s executive vice president and CEO, told VICE News of Delago’s second study soon after its publication.

“These are people in my opinion who are just ideologically opposed to what we’re doing,” Delgado countered Tuesday. “And so they’re trying to find anything they can to criticize us and to defame us, and I think that’s very unfortunate, because they don’t have the patients in mind.”

But it's the law

This controversy hasn’t stopped anti-abortion legislators from enshrining “abortion reversal” into state law, and some cases, expanding it.

This year, Arkansas Republican Gov. Asa Hutchinson signed into law a bill that will mandate that patients who’ve just taken mifepristone be informed that their abortion can still be reversed.

Bills that would require doctors to counsel patients about abortion reversal have also been proposed this year in Georgia, Kansas, North Carolina, Nebraska, and Oklahoma; they’ve already been signed into law in Kentucky and North Dakota, the Guttmacher Institute has found.

Despite the need for more research into the treatment, Delgado says it’s safe enough to recommend.

“There’s no reason to withhold the treatment, pending the other studies, because right now all the evidence shows that it is safe and effective,” he said. “And this is how we’ve done any other new treatment throughout the history of medicine.”

VICE News reached out to several state legislators who backed abortion reversal bills about Creinin’s study, and its impact on their proposals.

“If you talk to the doctors who have done this, it’s pretty convincing, and see the babies — and I have seen some of those babies — which are now thriving, growing people, that’s pretty good evidence in my mind,” said North Carolina Sen. Joyce Krawiec, a Republican. “But I would be very anxious to see the results of [Creinin’s] study as well.”

Kansas Gov. Laura Kelly, a Democrat, has not yet decided whether to sign an abortion reversal bill that recently passed the state legislature, her office said.

Creinin knows that legislators don’t have to pay attention to the results of his study, regardless of what he finds. But it’s important to test the treatment anyway, he said, as a doctor who cares for women. While a woman has never told him that she wanted to change her mind after taking mifepristone — and at least one study has indicated that most women are sure of their decision to get abortions — Creinin says it is possible.

“Rather than people doing shams of treatment and calling it ‘studies,’ the goal is to really find out, ‘Is this real or not?’” Creinin said. “So that if it’s not real, we can stop stupid laws from being passed. And so that, if it is potentially real, then we can at least understand what the right treatment is.”