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FAQ: How effective is medication abortion at terminating a pregnancy?


Medication abortion regimens are safe and effective during early pregnancy. For all three methods of medication abortion, efficacy decreases with increasing gestational age. The mifepristone and misoprostol regimen is 95%-98% effective through the first nine weeks of pregnancy. Recent research indicates that mifepristone and misoprostol can be used in the tenth week of pregnancy but with somewhat lower efficacy (≈92%).


The methotrexate and misoprostol regimen is highly effective in the first seven weeks of pregnancy (95%) but is less effective after 49 days (82% during the eighth week of pregnancy). 


The efficacy of misoprostol alone is variable and depends on both gestational age and regimen (65%-93%). The most recent studies on the use of misoprostol alone for early pregnancy termination report efficacy of 75%-85% through the first nine weeks. This efficacy is based on a regimen that is comprised of three 800 microgram doses taken 3 to 12 hours apart and administered bucally, sublingually, or vaginally. Alternatively, similar efficacy can be achieved with vaginal administration of 800 micrograms of misoprostol followed 24 hours later with another 800 micrograms administered vaginally.


If you have questions about medication abortion, please visit our frequently asked questions section.


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