This sheet is about exposure to mifepristone in pregnancy and while breastfeeding. This information should not take the place of medical care and advice from your healthcare provider.
What is mifepristone?
Mifepristone is a medication that is approved for use in combination with another medication called misoprostol, to medically terminate (end) a pregnancy that is less than 10 weeks along (70 days or less since the start of the last menstrual period). MotherToBaby has a fact sheet on misoprostol at: https://mothertobaby.org/fact-sheets/misoprostol-cytotec/.
Mifepristone has also been approved to treat high blood sugar levels (hyperglycemia) in people with a medical condition known as Cushing’s syndrome. Mifepristone has also been used to help dilate (open) the cervix, treat miscarriage, induce (start) labor, treat endometriosis, treat some forms of cancer, and other uses. Some brand names for mifepristone are Korlym® and Mifeprex®.
I am taking mifepristone, but I would like to stop taking it before becoming pregnant. How long does the drug stay in my body?
People eliminate medication at different rates. In healthy adults, it takes between 5 and 20 days for most of the mifepristone to be gone from the body.
I take mifepristone. Can it make it harder for me to get pregnant?
Mifepristone has been used as a contraceptive (to help prevent pregnancy). This means that taking mifepristone could make it harder to get pregnant.
Does taking mifepristone increase the chance for miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. Mifepristone can cause uterine contractions (when the muscles of the uterus get tight and then relax), which can increase the chance for miscarriage. The increased chance of miscarriage from using mifepristone depends on the how much is taken (dose), when in pregnancy it is taken (timing), use of other medications, and other factors.
Does taking mifepristone increase the chance of birth defects?
Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. Most infants born after exposure to mifepristone do not have birth defects. There are case reports of birth defects after mifepristone use during pregnancy. However, mifepristone is often used in combination with another medication called misoprostol, which has been linked with birth defects. This makes is hard to know if the reported birth defects are due to one medication, the combination of medications, or other factors.
Does taking mifepristone in pregnancy increase the chance of other pregnancy-related problems?
Studies have not been done to see if mifepristone increases the chance for pregnancy-related problems such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth).
Does taking mifepristone in pregnancy affect future behavior or learning for the child?
Studies have not been done to see if mifepristone increases the chance for behavior or learning issues.
Breastfeeding while taking mifepristone:
Mifepristone can enter breastmilk. In a study among 2 people who took a 1-time 200 mg mifepristone pill, the medication was not detected in the breastmilk. Among 10 people who took a 1-time 600 mg mifepristone pill, it was estimated that a fully breastfed infant would get a small amount (less than 1%) of the medication dose. The authors of this study have suggested that breastfeeding does not need to stop after a single dose of mifepristone. There are no data on breastfeeding when mifepristone is for long-term therapy to treat hyperglycemia. Because this medication can stay in the body for a while, the manufacturer has recommended pumping and discarding milk during long-term therapy and for 18 to 21 days after the last dose. Be sure to talk to your healthcare provider about all of your breastfeeding questions.
If a male takes mifepristone, could it affect fertility (ability to get partner pregnant) or increase the chance of birth defects?
Studies have not been done to see if mifepristone could affect fertility or increase the chance of birth defects above the background risk. In general, exposures that fathers or sperm donors have are unlikely to increase the risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.
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OTIS/MotherToBaby encourages inclusive and person-centered language. While our name still contains a reference to mothers, we are updating our resources with more inclusive terms. Use of the term mother or maternal refers to a person who is pregnant. Use of the term father or paternal refers to a person who contributes sperm.
