A new study suggests a possible alternative to the abortion pill Mifepristone, a drug that continues to be a target of lawsuits and legislation by abortion opponents.
But the potential substitute could further complicate the politics of reproductive health because it is also the key ingredient in a morning-after contraceptive 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 pills approved in the United States. (The other, the one-step BB plan, which does not require a prescription, contains a different drug and does not work to terminate a pregnancy, according to scientific evidence.)
In the study, 133 women who were up to nine weeks pregnant took double the dose of the ulipristal acetate contained in Ella, followed by misoprostol, the second drug used in the typical drug abortion regimen. All but four women completed termination of their pregnancies without further intervention, a 97% completion rate similar to the regimen using Mifepristone. (The others finished the trial with additional medications 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, lead author of the study and president of Gynuity Health Projects, a reproductive health research organization, said that after the Supreme Court struck down the nation’s right to abortion in 2022, she became increasingly more interested in a possible role for Ulipristal acetate, which has a similar chemical structure to mifepristone.
“I was thinking, there’s maybe something else we can do,” he said. “Another option. And this is already on the market. “
The study’s policy implications are complex because of their potential to blur the line between public perceptions of emergency contraception and abortion. For years, abortion opponents have opposed morning pills, saying they can cause miscarriages, and reproductive health experts have countered by pointing to scientific evidence that the pills do not terminate pregnancies but instead work to prevent pregnancy after sex.
Some reproductive health experts are concerned that research showing that a morning pill ingredient can be used for abortion could fuel attempts to crack down on emergency contraception and sow confusion that could strengthen the broader anti-abortion strategy .
Kristi Hamrick, spokeswoman for Students for Life of America, said her organization would “absolutely” consider litigation over Ella.
“The pro-life movement should be reclaimed,” Ms. Hamrick said. “We have argued for years that Ella acts 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 will put wind in the sails of abortion opponents who have said that things like contraceptives can be abortive,” she said, adding, “this study being released will be difficult, I think, to get abortion rights supporters to manage”.
But Ms. Ziegler said the study’s findings could also be “politically risky” 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 it could backfire.”
Reproductive health experts said the new study did not disprove science proving that morning-after pills do not induce miscarriages, because it involved a different dose of the drug.
Several experts said that because this was a relatively small first study without a comparison group of patients, more research was needed before ulipristal acetate should be used as a replacement 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 potential to end an embryo’s life, abortion advocates are now starting to use it as a substitute for the abortion drug mifepristone,” Dr. Donna Harrison, American Research Director of Pro -Life Pro-Life Obstetricians and gynecologists said in a statement. “The reason for this is simple. Ulipristal and mifepristone work the same way. “
She was already a target for some conservatives. Project 2025, a right-wing political model that has been strongly linked to the new Trump administration, said Ella should be removed from required insurance coverage of contraception under the Affordable Care Act because she is “a potential abortifacient.”
Mifepristone, the first pill in the standard two-drug abortion regimen, is the only drug approved specifically for abortion in the United States. Typically used through 12 weeks of gestation, Mifepristone stops the development of a pregnancy 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 physician and researcher at the University of California, 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 with 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 as abortion opponents have waged efforts to sharply limit the drugs across the country, most notably with a federal lawsuit against the Food and Drug Administration. The Supreme Court rejected that lawsuit last year, ruling that the original plaintiffs had no standing to sue, but the suit has since been revived with three states as plaintiffs.
Dr. Grossman, who wrote an editorial about the study, said the prospect of a replacement for Mifepristone was “certainly a promising discovery.” But, he added, “if because of this new evidence that at higher doses, ulipristal acetate could cause an abortion, that would lead to ulipristal acetate being taken off the market for emergency contraception, it would really, really bad.”
Perrigo, the company that makes Ella, released a statement saying that because the new study tested ulipristal acetate at a higher dose than an Ella pill and in combination with misoprostol, “there continues to be no evidence for demonstrate that, alone, Ella causes an abortion. ” The company added that “Ella is an FDA-approved emergency contraception pill that works before pregnancy.”
The study was conducted in Mexico City and was co-led by researchers there.
Scientists have long understood that hormone-based drugs might be able to perform different functions at different doses across the spectrum of a woman’s reproductive health cycle.
In Europe, researchers including Dr. Rebecca Gomperts, a Dutch doctor and founder of telemedicine organizations that provide abortion pills globally, are studying low doses of mifepristone as a weekly birth control pill. Dr. Gomperts said she considered the new ulipristal acetate study 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 take them away,” Dr. said. Paul Blumenthal, professor emeritus of obstetrics and gynecology at Stanford University who was part of an advisory group for the study.
Plan B is a much more widely used morning pill in the United States, but Ella is considered more effective for some women, including people who are overweight. Plan B must 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 can be fertilized, scientific studies have shown.
The claim by some abortion opponents that morning-after pills are abortion drugs is based on a theory that they might also prevent a fertilized egg from implanting in the uterus. Most scientific research has not found this to be the case.
For years, despite scientific evidence to the contrary detailed in a New York Times investigation, the FDA-approved label and packaging for the BB plan claimed that while the pill worked by blocking ovulation, there was the possibility that could prevent the implantation. In 2022, the agency changed the language to clarify that Plan B works only before fertilization, “will not work if you are already pregnant, and will not affect an existing pregnancy.”
The FDA label for Ella states that its “probable primary mechanism of action” is to stop or delay ovulation. The label adds that the drug can also affect implantation. Studies in recent years, however, suggest that Ella does not work by blocking a fertilized egg from implanting in the uterus.