Mifepristone use while Breastfeeding
Drugs containing Mifepristone: Mifeprex, Korlym
Mifepristone Levels and Effects while Breastfeeding
Summary of Use during Lactation
Limited information indicates that breastfeeding need not be interrupted after a single dose of mifepristone. A dose of 200 mg might be preferable to a 600 mg dose in nursing mothers
Maternal Levels. Twelve women (most 6 to 12 months postpartum) who had undergone a medical abortion using mifepristone and misoprostol provided milk samples for up to 5 days after the procedure for measurement of mifepristone. In the 2 women who received a single dose of 200 mg orally, mifepristone was undetectable (<5.6 mcg/L) in breastmilk at all times. Among the 10 women who received a single oral dose of 600 mg, average mifepristone breastmilk levels were 172 mcg/L on day 1 (n = 9) ; 66 mcg/L on day 2 (n = 9); 31 mcg/L on day 3 (n = 10); 24 mcg/L on day 4 (n = 4); and, 25 mcg/L on day 5 (n = 3). Breastmilk levels of mifepristone were highest in the samples collected between 6 and 9 hours after drug administration. Samples collected between 9 and 15 hours after the dose had much lower mifepristone levels. The authors estimated that a fully breastfed infant would receive a weight-adjusted dosage of 0.5% of the maternal dosage. They suggested that breastfeeding need not be interrupted after a single dose of mifepristone and that a dose of 200 mg might be preferable to a 600 mg dose in nursing mothers.
Infant Levels. Relevant published information was not found as of the revision date.
Effects in Breastfed Infants
Relevant published information was not found as of the revision date.
Possible Effects on Lactation
Based on animal data, some authors suggest that mifepristone used at term might shorten the onset of lactation, increase milk flow and increase the initial growth rate of breastfed infants. However, no human data are available.
1. Saav I, Fiala C, Hamalainen JM et al. Medical abortion in lactating women - low levels of mifepristone in breast milk. Acta Obstet Gynecol Scand. 2010. PMID: 20367522
2. Baird DT. Antigestogens. Br Med Bull. 1993;49:73-87. PMID: 8324617
3. Permezel M. The antiprogesterone steroid, RU 486 (mifepristone). Aust N Z J Obstet Gynaecol. 1990;30:77-80. PMID: 2189395
4. Ulmann A, Dubois C. Anti-progesterones in obstetrics, ectopic pregnancies and gynaecological malignancy. Baillieres Clin Obstet Gynaecol. 1988;2:631-8. PMID: 3069266
CAS Registry Number
- Contraceptives, Oral, Synthetic
- Contraceptives, Postcoital, Synthetic
- Hormone Antagonists
- Luteolytic Agents
- Menstruation-Inducing Agents
- Abortifacient Agents, Steroidal
LactMed Record Number
Information from the National Library of Medicine's LactMed Database.
Last Revision Date
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