What does a medication abortion entail?

Medication abortions terminate pregnancies with two drugs rather than a surgical procedure

February 24, 2023
A set of hands holding an orange box of Mifeprex, the name brand of mifepristone
Two drugs taken in sequence — mifepristone then misoprostol — can terminate a pregnancy through 10 weeks of gestation. [Robin Marty/Flickr | CC BY 2.0]

After overturning the national abortion protections afforded by Roe v. Wade, conservative legal groups are closing in on their next target: medication abortions. The same group that filed the case in Dobbs v. Jackson Women’s Health Organization have sued the FDA to remove its approval of mifepristone, a drug used in medication abortions. The complaint was filed last November in a federal court in Texas, and advocates worry it could have national ramifications for abortion access.

But what exactly is a medication abortion, and how does it work?

A medication abortion ends a pregnancy through medication instead of a surgical procedure; medication abortions make up more than half of all abortions in the US, according to the Guttmacher Institute, a reproductive health research organization. The regimen, approved by the FDA in 2000, involves two drugs taken in sequence: mifepristone followed by misoprostol. Together, they can terminate pregnancies up to 10 weeks of gestation.

Many studies have confirmed the drugs are effective and safe. A 2015 review of 20 studies found the drugs terminate 96% of pregnancies without needing a follow-up surgery, and severe side effects are rare; complications like hemorrhaging occur in only around 0.5% of cases.

The first drug in the sequence, mifepristone, halts the body’s preparation for pregnancy by blocking the hormone progesterone (often called the pregnancy hormone). The ovaries produce oscillating amounts of progesterone throughout the menstrual cycle. Mifepristone binds to progesterone receptors and stops the hormone from binding. 

Normally, progesterone triggers many different pathways to support pregnancy. It thickens the lining of the uterus, which makes it easier for a fertilized egg to implant and start growing. It inhibits the contractions that shed and push out that lining during menstruation. It builds a barrier of mucus in the cervix to ward off invading pathogens. 

But in the presence of mifepristone, progesterone can’t exert its effects on the uterus. The uterine lining stops thickening, the cervix softens, and the uterus contracts — actions that work against a developing pregnancy. 

Mifepristone alone is not an effective treatment for an abortion. Instead, it primes the uterus for a termination and misoprostol kicks it into gear. 

Misoprostol is a synthetic version of a prostaglandin, a compound produced by the body that triggers contractions in the uterus. The drug causes the uterus to contract and push out its contents. Misoprostol can be used alone for abortions, but it is more effective when taken after the prep work done by mifepristone. When taken alone — which is not approved by the FDA — it can take more time and more of the drug to complete the abortion. 

In the approved regimen, patients take 200 milligrams of mifepristone by mouth and then wait 24 to 48 hours to take 800 micrograms of misoprostol. Misoprostol can cause nausea and vomiting when taken by mouth, but those side effects are often reduced by putting the pill inside the vagina or letting it dissolve in the mouth, against the cheek. 

If the Texas case snakes its way up to the Supreme Court, it could result in the FDA removing its approval of mifepristone nationwide. Misoprostol-only abortions would remain accessible in states with abortion access. But it would add yet another barrier to the people seeking safe and reliable abortion care.

About the Author

Calli McMurray

Calli McMurray is a health journalist based in Brooklyn. She grew up in Texas (yeehaw!) and graduated from the University of Texas at Austin with a B.S. in neuroscience and a minor in English. Her work has appeared in STAT News, The Texas Observer, KFF Health News, and elsewhere.


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