Abortion pill reversal is the idea that taking extra progesterone after the first abortion pill, mifepristone, can stop the abortion and save the pregnancy. Major medical groups call it unproven, because many pregnancies continue after the first pill even with no treatment at all.1The American College of Obstetricians and Gynecologists. Medication Abortion “Reversal” Is Not Supported by Science The larger safety concern is heavy bleeding, which can happen to anyone who stops partway through, whether or not they take progesterone.
How the Abortion Pills Work and What Reversal Tries to Do
A medication abortion usually uses two drugs. Mifepristone comes first. A day or two later, misoprostol makes the uterus contract and empty. The first pill starts the process but often doesn’t finish it alone, and the second pill causes the cramping and bleeding that complete it.
Mifepristone works by blocking progesterone, a hormone the body needs to keep the lining of the uterus in place during early pregnancy.2Synapse. What is the mechanism of Mifepristone? The drug attaches to the body’s progesterone receptors more tightly than progesterone itself does, so the hormone can’t do its job.3Synapse. What is the mechanism of Mifepristone? The lining then breaks down and the embryo comes away from it.4Synapse. What is the mechanism of Mifepristone?
Reversal tries to win those receptors back. The two compounds compete for the same spot, so the idea is that enough extra progesterone could push mifepristone off.5PubMed Central. Progesterone-mediated reversal of mifepristone-induced pregnancy termination in a rat model: an exploratory investigation Because mifepristone grips the receptor more strongly, very high progesterone doses would be needed.6PubMed Central. Progesterone-mediated reversal of mifepristone-induced pregnancy termination in a rat model: an exploratory investigation In pregnant rats, progesterone given after mifepristone kept the pregnancy going in about 8 in 10.7Naunyn-Schmiedeberg’s Archives of Pharmacology. Progesterone-Mediated Reversal of Mifepristone-Induced Pregnancy Termination in an Animal Model: An Exploratory Investigation A result in rats doesn’t show the same thing happens in people.
Reversal is only ever discussed in the gap between the two pills. Once the second pill has been taken, no one offers progesterone as a way back.
Does Abortion Pill Reversal Work
Many pregnancies continue after the first pill alone. Without any reversal treatment, between 8% and 46% of pregnancies were still ongoing one to two weeks after mifepristone alone.8PubMed. Continuing pregnancy after mifepristone and “reversal” of first-trimester medical abortion: a systematic review They were more likely to continue with lower mifepristone doses and further along in pregnancy.9PubMed. Continuing pregnancy after mifepristone and “reversal” of first-trimester medical abortion: a systematic review Any reversal success rate has to beat this natural rate to mean anything.
The reports claiming success have serious flaws. The main report behind reversal claimed about 64% to 68% success with injected or high-dose oral progesterone.10PubMed. A case series detailing the successful reversal of the effects of mifepristone using progesterone A larger report of 754 women treated said 47% had a live birth, compared with about 25% after mifepristone alone.11The New England Journal of Medicine. Abortion “Reversal” — Legislating without Evidence But it left out 27% of women, including some found by ultrasound to have already lost the pregnancy before treatment.12The New England Journal of Medicine. Abortion “Reversal” — Legislating without Evidence It also dropped women who stopped being followed before 20 weeks, which likely made success look higher.13The New England Journal of Medicine. Abortion “Reversal” — Legislating without Evidence Those numbers can’t be fairly compared with mifepristone alone.
Success rates mislead without a comparison group. A woman who has a baby after reversal may have kept the pregnancy anyway, and without a matched untreated group you can’t tell what progesterone added. A fair test randomly gives some people progesterone and others a dummy pill, then compares the groups the same way.
When the data are pooled, progesterone doesn’t clearly help. Across 561 people given progesterone after mifepristone, 48% had pregnancies that continued.14PubMed Central. Reversal of medication abortion with progesterone: a systematic review Up to 7 weeks of pregnancy, about 42% continued with progesterone versus 22% with mifepristone alone.15PubMed Central. Reversal of medication abortion with progesterone: a systematic review At 7 to 8 weeks, about 62% continued with progesterone versus 50% without it.16PubMed Central. Reversal of medication abortion with progesterone: a systematic review Yet the data are mostly poor quality and show no clear advantage for progesterone over doing nothing.17PubMed Central. Reversal of medication abortion with progesterone: a systematic review The one properly designed trial comparing progesterone with a dummy pill was stopped before it could measure whether progesterone works.18PubMed. Mifepristone Antagonization With Progesterone to Prevent Medical Abortion: A Randomized Controlled Trial
Skipping the second pill gives a real chance the pregnancy continues, with or without progesterone, so progesterone isn’t a rescue that must be started within hours. Symptoms alone can’t tell you whether the pregnancy is continuing; only an ultrasound shows whether it is still growing.
Is It Safe to Stop After the First Pill
A trial of progesterone after mifepristone was stopped after only 12 women joined, because three had severe bleeding that needed an ambulance to the hospital.19NPR. Safety Problems Lead To Early End For Study Of ‘Abortion Pill Reversal’ One of those had taken progesterone and two had taken a dummy pill, and one needed a blood transfusion.20PubMed Central. Reversal of medication abortion with progesterone: a systematic review Two of the women needed a procedure to empty the uterus.21PubMed Central. Reversal of medication abortion with progesterone: a systematic review People in early pregnancy who take only mifepristone may face a high risk of heavy bleeding.22PubMed. Mifepristone Antagonization With Progesterone to Prevent Medical Abortion: A Randomized Controlled Trial
The bleeding happens because the first pill has already started breaking down the lining of the uterus. Without the second pill to help the uterus contract and empty, tissue can come away partly and unevenly, and the bleeding can continue until it is treated.
Certain signs call for urgent care. Soaking through two thick pads an hour for two hours in a row is a reason to get help right away, not to wait and see. Fainting, dizziness, or a racing heart can mean a serious amount of blood has been lost, even if the bleeding looks manageable. Fever, or discharge with a foul smell, can point to infection. Go to an emergency room and tell the staff you took mifepristone, since that changes how they assess you.
Progesterone itself is a familiar drug. It is already prescribed in pregnancy for other reasons, such as low progesterone.23Bakersfield Pregnancy Center. Is Abortion Pill Reversal Real? The bigger worry is not the hormone but leaving an abortion unfinished without close medical follow-up.
Can the First Pill Harm a Continuing Pregnancy
Mifepristone alone looks low risk. Current guidelines say it is not known to cause birth defects, though human evidence is limited.24PubMed. Congenital and Fetal Effects After Mifepristone Exposure and Continuation of Pregnancy: A Systematic Review In one study of 105 pregnancies that continued after mifepristone, 94 ended in live births and major birth defects occurred at about the usual rate.25Alight PC. What Happens if You Only Take the First Abortion Pill (Mifepristone)? Reviews found that many defects seen after exposure were explained by other causes.26PubMed. Congenital and Fetal Effects After Mifepristone Exposure and Continuation of Pregnancy: A Systematic Review
The second pill is a different story. Exposure to mifepristone and/or misoprostol has been linked to higher rates of some rare defects, including fluid on the brain and missing parts of fingers or limbs.27PubMed. Risk of teratogenicity in continued pregnancy after gestational exposure to mifepristone and/or misoprostol: a systematic review and meta-analysis A possible effect can’t be fully ruled out, especially if misoprostol was taken.
If the pregnancy continues, tell your prenatal care provider which pills you took and on what dates, so they can judge how much exposure there was. Say clearly whether you took any misoprostol, even a single dose, because the concern about birth defects is greater with that drug. Ask whether a detailed anatomy ultrasound around 18 to 20 weeks makes sense for you. Apart from that, ordinary prenatal care applies.
What the Reversal Treatment Involves
Regimens vary, but they all involve weeks of high-dose progesterone:
- By mouth: 400 mg progesterone twice on day 1, then twice daily on days 2 and 3, then nightly for at least two weeks.28AAPLOG. Progesterone Protocols for The Attempted Reversal of Mifepristone
- In the vagina: the same capsules and schedule, for those who can’t swallow them or take shots.29AAPLOG. Progesterone Protocols for The Attempted Reversal of Mifepristone
- Injection: 200 mg into the buttock muscle daily for three days, then every other day to day 14, then twice weekly.30AAPLOG. Progesterone Protocols for The Attempted Reversal of Mifepristone
- One trial: 400 mg twice daily for 3 days, then 400 mg nightly for a 19-day course.31PubMed. Progesterone after mifepristone: A pilot prospective single arm clinical trial for women who have changed their mind after commencing medical abortion
In practice, promoters stress starting within hours of the first pill, but that urgency rests on the theory rather than on proof that earlier is better. Many people reach reversal providers through hotlines advertised in searches or on social media. The provider will often do an ultrasound at the start to check whether the pregnancy is still growing. Progesterone can cause drowsiness, so bedtime doses are common.
The clinic that gave you the pills can arrange follow-up and an ultrasound, and an obstetrician or emergency room can also check for bleeding. Whichever provider you choose, ask what they will do if heavy bleeding starts.
Why Doctors’ Groups Reject It While Some Laws Promote It
The American College of Obstetricians and Gynecologists does not support prescribing progesterone to stop a medication abortion.32The American College of Obstetricians and Gynecologists. Medication Abortion “Reversal” Is Not Supported by Science UK obstetric, midwife and sexual health bodies agree it is unproven and unethical.33BJOG: An International Journal of Obstetrics & Gynaecology. Joint statement on ‘Abortion reversal’: RCOG, FSRH, RCM and BSACP The FDA has not reviewed progesterone for this use, but doctors may legally prescribe it off-label, meaning for a use the FDA hasn’t approved.34NPR. Controversial Abortion Reversal Regimen Is Put To The Test
Some laws point the other way. As of 2021, 14 US states, mostly in the Midwest and South, required patients be told about reversal before an abortion.35PubMed Central. Medication Abortion “Reversal” Laws: How Unsound Science Paved the Way for Dangerous Abortion Policy Reversal ads were shown on Facebook 18.4 million times since 2020 and appear on most abortion-related Google searches in several cities.36the Guardian. Facebook and Google condemned over ads for ‘abortion pill reversal’
If you land on a reversal website, check whether any success rate is compared with women who took nothing, since a number on its own proves little. Look at who runs the site and whether it also offers follow-up for people who choose to finish the abortion. Note whether it warns about heavy bleeding; one that leaves it out is giving only part of the picture. A pregnancy center is not always a licensed medical clinic, so ask whether a doctor or nurse will be involved in your care.
What to Do If You Changed Your Mind After the First Pill
Not taking the second pill is the step that most affects whether the pregnancy can continue. Then contact your abortion provider or another doctor and say you’ve changed your mind. An ultrasound in a week or two shows whether the pregnancy is still growing. Given the bleeding risk, keep a way to reach emergency care for the first days.
If you’re unsure what you want, you don’t have to decide in the first hour. Waiting does carry a bleeding risk, so stay in touch with a provider, and talk to someone you trust, not just an ad hotline.
If the pregnancy continues, start prenatal care and share your pill history. You can still choose to finish the abortion later with a provider.
If the pregnancy ends anyway, bleeding and cramping may mean it is passing, and this can happen even if you did not take the second pill. A provider can confirm that the process is complete and treat any tissue that remains. Feeling grief, relief, or both is common and does not mean you did anything wrong.