Abortion pill mifepristone: An explainer and research roundup about its history, safety and future

On June 13, the Supreme Court justices in a unanimous decision preserved access to mifepristone, a medication that’s used for the safe termination of early pregnancy, writing that “federal courts are the wrong forum for addressing the plaintiffs’ concerns about FDA’s actions.” This piece aims to help inform the narrative on medication abortion with scientific evidence.

What is Medication Abortion?

Medication abortion is also known as abortion with pills or medical abortion. It differs from a surgical abortion, in which tissue from the pregnancy is removed from the uterus during a surgical procedure. Medication to terminate a pregnancy typically involves two drugs: mifepristone (Mifeprex, RU-486, “the abortion pill”) and misoprostol (Cytotec).

Mifepristone stops progesterone, a hormone needed to sustain pregnancy. Misoprostol tells the uterus to contract to empty its contents. Cervical dilation (opening) also happens at this time, allowing for the tissue to be expelled from the uterus. The drugs are taken 24 to 48 hours apart.

Effectiveness and Eligibility

The Food and Drug Administration has approved medication abortion for up to 10 weeks of pregnancy and the World Health Organization authorizes its use for up to 12 weeks. According to Planned Parenthood, the effectiveness of a medical abortion varies depending on how far along the pregnancy is:

• For someone 8 weeks pregnant or less, it is effective in 94–98 out of 100 people.
• For someone 8–9 weeks pregnant, it is effective in 94–96 out of 100 people.
• For someone 9–10 weeks pregnant, it is effective in about 91–93 out of 100 people.
• For someone 10–11 weeks pregnant, it is effective in about 87 out of 100 people; with extra medication, it is effective in about 98 out of 100 people.

Many physicians will recommend medical abortion no later than 10 weeks in the outpatient setting; later it may be done in a supervised hospital setting so health practitioners can monitor the pregnant person’s status.

Legal Challenges and Regulatory History

The legal future of mifepristone had hung in the balance for several months. In August 2023, the 5th U.S. Circuit Court of Appeals ruled that mifepristone should not be prescribed past the seventh week of pregnancy, prescribed via telemedicine, or shipped to patients through the mail. In September, the Justice Department asked the Supreme Court to consider a challenge to that ruling. On Dec. 13, 2023, the Supreme Court justices announced that they would take up the case on the availability of mifepristone. The justices heard oral arguments on March 26, 2024 before issuing the June 13 ruling.

Meanwhile, abortion is on the ballot in four states this year so far. Measures have also been proposed in several other states, with initiatives that aim to ban, restrict, or expand abortion rights. It’s important for journalists covering abortion to have a good understanding of medication abortion so that they can better inform their audiences. It is endorsed by several organizations, including the American College of Obstetricians & Gynecologists and the American Medical Association.