A new study suggests a possible alternative to the abortion pill mifepristone, a drug that continues to be the target of lawsuits and legislation by abortion opponents.
But the potential substitute could further complicate reproductive health policy because it’s also the key ingredient in a morning-after pill.
The new study, published Thursday in the journal NEJM Evidence, involved a drug called ulipristal acetate, the active ingredient in the prescription contraceptive Ella, one of two types of morning-after pills approved in the United States. (The other, Plan B One-Step, which doesn’t require a prescription, contains a different drug and doesn’t work in a way that could end a pregnancy, according to scientific evidence.)
In the study, 133 women who were up to nine weeks pregnant received double the dose of ulipristal acetate contained in Ella, followed by misoprostol, the second drug used in the standard medical abortion regimen. All but four of the women completed their pregnancy termination without further intervention, a 97 percent completion rate that is similar to the regimen using mifepristone. (The others completed the procedure with additional medication or a procedure.)
There were no serious complications and the study concluded that the use of ulipristal acetate in the two-drug abortion regimen was safe.
Dr. Beverly Winikoff, the study’s lead author and president of Gynuity Health Projects, a reproductive health research organization, said that after the Supreme Court overturned the nation’s right to abortion in 2022, she became increasingly interested in a possible role of ulipristal. acetate, which has a similar chemical structure to mifepristone.
“I thought, maybe there’s something else we can do,” he said. “Another choice. And that’s already on the market.”
The political implications of the study are complicated by their potential to blur the line between public perception of emergency contraception and abortion. For years, abortion opponents have opposed the morning-after pill, saying it can cause abortions, and reproductive health experts have countered by pointing to scientific evidence that the pills don’t end pregnancy but instead work to prevent pregnancy after sex. .
Some reproductive health experts worry that research showing an ingredient in the morning-after pill can be used to induce abortion could fuel efforts to crack down on emergency contraception and create confusion that could bolster the broader anti-abortion strategy.
Kristi Hamrick, a spokeswoman for Students for Life of America, said her organization would “absolutely” consider legal action for Ella.
“The pro-life movement must be vindicated,” said Ms. Hamrick. “We’ve been arguing for years that Ella works as an abortionist.”
Mary Ziegler, a law professor and abortion expert at the University of California, Davis, said the study could present challenges for both sides of the abortion debate.
“It’s going to put wind in the sails of abortion opponents who say things like contraceptives can be abortifacient,” he said, adding, “This study coming out is going to be difficult, I think, for abortion rights advocates to handle.”
However, Ms. Ziegler said the study’s findings could also be “politically dangerous” for abortion opponents because public support for contraception is high and many voters in conservative states have approved ballot measures protecting abortion rights. “I think it’s one of those things that will tempt social conservatives to push probably faster than politics would currently allow in the direction of regulating contraception,” he said. “And I think that could backfire.”
Reproductive health experts said the new study did not disprove science showing that morning-after pills do not cause abortions because they included a different dose of the drug.
Several experts said that because it was a relatively small first study with no patient comparison group, more research was needed before ulipristal acetate could be used as a substitute for mifepristone in the two-drug regimen. “We cannot change clinical practice based on this study,” said Kelly Cleland, a researcher who is the executive director of the American Society for Emergency Contraception.
Abortion opponents said they were not surprised by the study’s findings.
“After years of denying ulipristal acetate’s ability to end the life of a fetus, abortion advocates are now beginning to use it as a substitute for the abortion drug mifepristone,” said Dr. Donna Harrison, director of research for the American Association of Pro- Life. Obstetricians and Gynecologists, it is stated in an announcement. “The reason for this is simple. Ulipristal and Mifepristone work in the same way.
Ella was already a target of some conservatives. Project 2025, a right-wing policy initiative that has been closely associated with the new Trump administration, said Ella should be stripped of required contraceptive insurance coverage under the Affordable Care Act because she is “potentially abortive.”
Mifepristone, the first pill in the standard two-drug abortion regimen, is the only drug specifically approved for abortion in the United States. Usually used up to 12 weeks of pregnancy, mifepristone stops a pregnancy from developing by blocking the hormone progesterone. The second drug, misoprostol, is taken 24 to 48 hours later and causes contractions similar to a miscarriage.
Ulipristal acetate is in the same class of drugs as mifepristone and also blocks the activity of progesterone, a hormone that prepares the uterus to receive and hold an embryo, said Dr. Daniel Grossman, a reproductive health physician and researcher at the University of California, Berkeley. San Francisco, who was not involved in the new study.
In the study, a 60-milligram dose of ulipristal acetate (double the 30 milligrams in Ella) was replaced by mifepristone and followed by misoprostol, which has various medical uses and has not been targeted as much by abortion opponents. (Misoprostol can also facilitate an abortion on its own, but is considered more effective in a combination regimen.)
Reproductive health experts said they welcomed the search for alternatives to mifepristone because abortion opponents are pushing to drastically limit the drug across the country, notably with a federal lawsuit against the Food and Drug Administration. The Supreme Court threw out that lawsuit last year, ruling that the original plaintiffs lacked standing to sue, but the lawsuit has since been revived with three states as plaintiffs.
Dr. Grossman, who wrote an article on the study, said the prospect of a mifepristone substitute was “certainly a promising finding.” But, he added, “if because of this new evidence that at higher doses, ulipristal acetate could cause abortion, that would lead to the withdrawal of ulipristal acetate from the market for emergency contraception, that would be very bad indeed.”
Perrigo, the company that makes Ella, issued a statement saying that because the new study looked at ulipristal acetate at a higher dose than an Ella pill and in combination with misoprostol, “there continues to be no evidence to show that, on its own , Ella induces an abortion.” The company added that “Ella is an FDA-approved emergency contraceptive pill that works before pregnancy occurs.”
The study was conducted in Mexico City and was jointly conducted by researchers there.
Scientists have long understood that hormone-based drugs may be able to play different functions at different doses along the spectrum of a woman’s reproductive health cycle.
In Europe, researchers, including Dr. Rebecca Gomperts, a Dutch physician and founder of telemedicine organizations that provide abortion pills worldwide, are studying low-dose mifepristone as a weekly birth control pill. Dr. Goberts said she considered the new study of ulipristal acetate sufficient to prescribe the drug off-label in combination with misoprostol.
“The more uses we have for these drugs, the harder it will be for people to get off them,” said Dr. Paul Blumenthal, professor emeritus of obstetrics and gynecology at Stanford University, who served on an advisory panel for the study.
Plan B is a much more widely used morning-after pill in the United States, but Ella is considered more effective for some women, including those who are overweight. Plan B is meant to be taken within three days of unprotected sex, while Ella can be taken within five days.
Both pills prevent pregnancy by blocking ovulation, the release of eggs from the ovaries that occurs before the eggs are fertilized, scientific studies have shown.
The claim by some anti-abortionists that morning-after pills are abortion drugs is based on a theory that they may also prevent a fertilized egg from implanting in the uterus. Most scientific research has found no such thing.
For years, despite scientific evidence to the contrary detailed in a New York Times investigation, the FDA-approved label and packaging for Plan B One-Step said that while the pill worked by preventing ovulation, there was a chance it could prevent the implantation. In 2022, the agency changed the language to make clear that Plan B works only before conception, “will not work if you are already pregnant, and will not affect an existing pregnancy.”
The FDA label for Ella says its “probable primary mechanism of action” is to stop or delay ovulation. The label adds that the drug may also interfere with implantation. Studies in recent years, however, show that Ella does not work by preventing a fertilized egg from implanting in the uterus.
