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Boxes of the drug mifepristone sit on a shelf at the West Alabama Women's Center in Tuscaloosa, Ala., March 16, 2022. (AP Photo/Allen G. Breed, File)

Colorado’s Medical Board on Thursday will attempt to decide something no other regulatory body in the country has: whether a controversial treatment to try to “reverse” the effects of an abortion pill is something doctors should be providing.

The evidence for the practice is spotty. Federal authorities have not approved it. No clinical trials — the most rigorous type of research — have validated its safety or its efficacy in humans. As a result, the nation’s leading organization for OB-GYN doctors says that the idea of abortion reversal “is not supported by science.”

This is not to say that the practice has been thoroughly debunked, though. Proponents of the practice point to studies involving rats, as well as a large case series — a less rigorous type of research — to argue that reversal is possible and something that should be available in the rare instances where a pregnant patient wants to try.

If those were the only factors at play in the Medical Board’s decision, this debate would look like many others in the scientific and medical communities. When data is scant, what’s the best course of action? How much evidence is enough for patients to have the right to try?

But, instead, Thursday’s debate is taking place against the backdrop of the nationwide turmoil around abortion care and reproductive rights. It will take place as states across the country pass restrictive abortion laws that are pushing more and more women to Colorado to receive care. It will take place as social media posts related to abortion reversal have skyrocketed following the Supreme Court’s overturning of Roe v. Wade.

The only reason it’s taking place at all is because Colorado lawmakers passed a first-of-its-kind law earlier this year declaring abortion pill reversal to be unprofessional conduct for doctors, nurses and pharmacists, a law that an anti-abortion clinic is challenging in court.

And now all of this attention will turn to deciding whether medication abortion reversal is supported enough by science for doctors not to be punished for providing it — and that science rests on awfully spindly legs.

Demonstrators gather to protest Senate Bill 8, the new Texas law banning abortion after six weeks into a pregnancy, on Saturday, Sept. 4, 2021, at the Colorado State Capitol. (Olivia Sun, The Colorado Sun)

How did we get here?

Across the country, abortions are increasingly induced through pills. In Colorado, for instance, about 70% of patients receiving abortion care at Planned Parenthood receive a medication abortion.

A medication abortion typically involves two steps. First, a patient takes a drug called mifepristone. Then, generally within 48 hours, they take a second drug called misoprostol.


So-called medication abortion “reversal” seeks to work in the interval between the drugs. If a patient wants to stop the abortion after taking mifepristone, a medical provider will give them a high dose of the hormone progesterone in an attempt to counteract the effects of the mifepristone and preserve the pregnancy.

The practice is commonly promoted by religious-based, anti-abortion clinics and doctors.

“We’re not going to take away their choice to choose abortion; why would we take away their choice not to continue that abortion?” Stacy Swagger, a nurse who is the executive director of the Cañon City Pregnancy Center, an anti-abortion clinic that provides referrals for reversal, said during a public meeting earlier this summer where people could provide input on the Medical Board’s proposed rules.

Many of the places that offer reversal or provide referrals for it are the same places that critics condemn as “fake clinics” that do not provide comprehensive pregnancy care but instead exist to persuade women to carry pregnancies to term.

That prompted Democratic lawmakers to pass a bill this year declaring medication abortion reversal to be “unprofessional conduct” — meaning doctors, nurses and pharmacists who engage in it could have their license sanctioned.

“The reason that myself and other sponsors brought these rules is because we feel that pregnant people are going into these anti-abortion and pregnancy clinics and being shamed into practices that are not OK,” state Sen. Faith Winter, D-Westminster, said during another public meeting on the proposed rules.

At the insistence of Gov. Jared Polis, though, the bill was amended to contain a provision stating that the unprofessional conduct designation could be overturned if the state medical, nursing and pharmacy boards all passed resolutions declaring abortion reversal to be a “generally accepted standard of practice.”

That led to the rulemakings, which begin Thursday with the Medical Board’s. The nursing and pharmacy boards will take up the issue in September.

The Medical Board has already released a draft rule that proposes not automatically declaring abortion pill reversal to be unprofessional conduct, but instead deciding to look at complaints on a case-by-case basis. The board must still decide whether to adopt that rule or write a different one.

Thursday’s hearing starts at 9 a.m. and is virtual — there’s no in-person attendance option. It will, though, include a time for public comment. To sign up to speak or to get a link to participate virtually, see the meeting notice on the Medical Board’s website.

What does the science say?

There have been no completed clinical trials in humans that assess whether abortion pill reversal actually works.

Proponents sometimes point to studies involving rats, such as one released earlier this summer by researchers at the small, Catholic-affiliated Franciscan University of Steubenville that found administering progesterone after mifepristone could prevent abortion in 81% of instances.

But the most commonly cited research comes from a San Diego-based family physician named George Delgado. In 2018, Delgado published a case series following 547 women worldwide over a four-year period who said they had taken mifepristone and sought medication abortion reversal. Of those, 48% had their pregnancies continue.

“It appears based on low-level evidence that taking high-dose progesterone potentially doubles your likelihood of having a continuing pregnancy,” said Dr. Thomas Perille, a retired internal medicine and hospital medicine physician and president of Democrats for Life of Colorado who supports allowing doctors to provide reversal treatment. “Very few things in medicine cause a 50% decrease in mortality.”

Delgado’s research has notable limitations, though.

Patients were selected for inclusion because they called a hotline seeking information on abortion reversal, meaning they were essentially channeled through advocacy organizations. No information is included about health side effects that patients suffered — and little is reported, period, on patients whose pregnancies did not survive.

The study was also not placebo-controlled, though supporters argue that such a study would be unethical to do because it would create an added risk of abortion occuring in a wanted pregnancy.

“They view that pregnancy as a wanted pregnancy,” Perille said of women seeking reversal. “It flips the narrative completely. You do everything you can to protect and save that developing baby.”

Attendees wave placards during a rally to protest the one-year anniversary of Colorado’s abortion law, the Reproductive Health Equity Act, Tuesday, April 4, 2023, outside the State Capitol in downtown Denver. (AP Photo/David Zalubowski)

To opponents of reversal, these study flaws render the Delgado research essentially meaningless. The lack of placebo-control is especially important because some patients who take only mifepristone will see their pregnancies continue without any further intervention. (Delgado’s study estimates this percentage at 25%, but some studies have found higher rates, up to 50%.)

“All of this falls in a realm of how you would never want medical care to work,” said Dr. Mitchell Creinin, an OB-GYN at UC Davis Health and an expert on abortion care. “We have no idea first of all if it works. We have no idea if it works differently for people of diff gestational ages. I have no idea how to counsel people about it.”

Only a controlled clinical trial can begin to answer some of those questions. So Creinin decided to do one himself.

What did the one clinical trial find?

To conduct a placebo-controlled clinical trial, Creinin recruited patients seeking surgical abortions. He asked if they would take mifepristone first and then receive either progesterone or placebo — the trial was blinded, so Creinin had no idea which patients were in which groups. At the end of their study participation, all patients with continuing pregnancies would be provided a surgical abortion, in keeping with their wishes.

Creinin and his coauthors planned to enroll 40 patients in the trial, but they had only 10 — five in each group — when Creinin chose to stop the study. Three patients had experienced severe bleeding, including one who required a transfusion.

“These are healthy people who don’t need this,” Creinin said he thought at the time.

The three patients happened to break down as one in the group receiving progesterone and two, including the patient requiring a transfusion, in the placebo group. Proponents of abortion pill reversal will sometimes cite this as additional evidence that reversal is the safer option for women who don’t want to go through with an abortion.

But Creinin said the sample sizes are so small that they are unreliable.

“You can’t use any results from my study to show that it works,” he said. “The statistics aren’t there.”

There is one takeaway that some doctors have drawn from the study. Dr. Rebecca Cohen, an OB-GYN with UCHealth and a professor at the University of Colorado School of Medicine, said the study shows a potential side effect of stopping a medication abortion after taking mifepristone, regardless of whether a patient then takes progesterone or not.

“We recognize that there is risk to starting the process and not continuing with misoprostol,” she said.

Planned Parenthood of the Rocky Mountains is seen on July 7, 2022, near downtown Denver. (Olivia Sun, The Colorado Sun via Report for America)

How many people seek abortion pill reversal?

While Colorado keeps detailed data on the number of abortions that occur in the state, there is no reliable figure for how many people seek to reverse a medication abortion.

Perille said 31 people from Colorado last year contacted the abortion pill reversal hotline operated by Heartbeat International. The number represents 0.2% of the more than 14,000 abortions in the state in 2022, though it’s not clear how many of those who called the hotline actually went through with attempting reversal.

Numbers are also difficult to come by nationally. In 2019, Nebraska joined a growing number of conservative states in passing a law requiring abortion providers to tell patients that reversal is an option. The law also required doctors to report to the state when they attempt a medication abortion reversal, and state officials are required to compile anonymized data from those reports to release to the public.

The Nebraska Department of Health and Human Services did not respond to three email requests from The Colorado Sun seeking information about those reports. A spokesman for the ACLU of Nebraska, which opposed the 2019 law, said his organization has never seen any of the reports on abortion reversal in the state, either, making it unclear whether an attempted reversal has occurred in the past four years.

To Creinin — who said he has never had a patient tell him they regret starting a medication abortion — the scarcity of reversal attempts is part of a larger narrative.

“It’s all part of the anti-choice publicity to lead down the path of saying that women change their mind frequently and women shouldn’t be allowed to make a choice in the first place,” he said.

Cohen said she has, rarely, had patients change their minds over the years, which is why she said she spends lots of time at the beginning talking with patients and making sure they know their options.

“When people are hesitant — which they occasionally are — we really reinforce that the best thing to do if they are not sure is not to start,” she said.

John Ingold is a co-founder of The Colorado Sun and a reporter currently specializing in health care coverage. Born and raised in Colorado Springs, John spent 18 years working at The Denver Post. Prior to that, he held internships at...