Study of So-Called 'Abortion Reversal' Stopped Early After Women Went to ER With Serious Bleeding

A pill of mifepristone, also called RU-486.
Photo: Getty Images

New research out Thursday starkly highlights the dangers of so-called “abortion reversals,” an unproven practice condemned by most medical experts. Scientists were forced to prematurely end a trial of pregnant women testing out the procedure after three volunteers experienced severe hemorrhaging that sent them to the emergency room.

“Abortion reversals” are alleged by anti-choice advocates and a minority of doctors as a way for women to keep a viable pregnancy after having taken the first of two separate medications that can safely induce an abortion during the first 10 weeks of gestation. Proponents of this unproven procedure suggest giving patients a high dose of progesterone, a key sex hormone that regulates a woman’s reproductive system. The progesterone allegedly blocks the first pregnancy-ending drug, called mifepristone, from binding to cell receptors, canceling out its effects.

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Anti-choice advocates have pushed through laws, with some success in states like Arkansas, that force doctors to claim to patients that they can get their medication abortions reversed. But most relevant doctors and organizations, such as the American College of Obstetricians and Gynecologists, have decried the practice entirely. They’ve argued—correctly—that there’s no good evidence the treatment works and that it could endanger their patients’ health. The little supporting evidence that does exist has so far come from isolated case reports.

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Despite agreeing with the medical consensus, the authors of this new study wanted to help settle the debate by conducting a randomized clinical trial, considered the gold standard of scientific evidence.

“As a researcher and clinician, I always want to find true answers and patients deserve the truth all of the time,” study author Mitchell Creinin, a gynecologist and researcher at the University of California Davis, told Gizmodo via email.

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Creinin and his team consciously recruited women further along in their pregnancy scheduled to get a surgical abortion, who were asked to delay the procedure for two weeks.

“The design and recruitment was intended to include a population of women that, in the end, would not be upset if the treatment worked or did not work. This type of design is how all drug development trials are designed,” he noted.

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At the start of the two-week delay, the women were all given a dose of mifepristone. Then they were randomized into two groups: One group was given daily doses of progesterone, and the other a simple placebo. They would stay in the study until their two-week follow-up visit or their pregnancy ended, whichever came first.

The study was originally intended to study 40 women. But it ended after only 12 patients had been enrolled. Three women—one in the progesterone group and two in the placebo group—experienced heavy bleeding soon after taking mifepristone. Though all three sought emergency care and one woman required a blood transplant, they thankfully didn’t experience any further serious complications and had their abortions completed surgically.

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It’s more than likely that the women’s bleeding was caused by them not finishing the full course of their treatment. Typically, women also take a dose of the drug misoprostol no less than two days after taking mifepristone (while either drug can induce abortion by themselves, their effectiveness is over 95 percent when taken together). And in this study at least, taking progesterone doesn’t seem to prevent the complication from happening. The possibility of endangering more women was enough for the authors to cut the study short.

In addition to the bleeding cases, two women (one in each group) also dropped out and had a surgical abortion early, citing side-effects such as nausea, vomiting, and some light bleeding. Excluding these cases, four out of five women in the progesterone group and two of five women in the placebo group were still pregnant by the end of the two-week span. But because of the small sample size, the authors say it’s not enough evidence either way to suggest that “abortion reversals” work. And given the health issues that arose, it’s yet more evidence these procedures could needlessly hurt women.

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“This does further the case that using progesterone to halt a medical abortion is not proven or known to be safe,” Creinin said.

The study’s findings were published Thursday in the journal Obstetrics & Gynecology.

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While Creinin and his team aren’t saying that halting an in-progress abortion is impossible, they argue it should strictly be considered an experimental procedure—one that states shouldn’t be forcing doctors to tell their patients is safe and effective. And it’s not something he plans to study further in the context of a clinical trial.

“I need a reason to want to do a study. If I have no reason to believe it is effective, then why do any more studies if it can be dangerous?” he said.

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About the author

Ed Cara

Science writer at Gizmodo and pug aficionado elsewhere