Medication abortion regimens can be safely and effectively during
early pregnancy. For all three methods of
medication abortion, efficacy decreases with increasing gestational
age. The mifepristone and misoprostol regimen is the most effective
(95%-98%) and can be used throughout the first nine weeks of
pregnancy. 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 suggest an efficacy rate of 75%-85%.
This efficacy is based on the vaginal administration of 800 micrograms of misoprostol followed 24 hours later with another 800 micrograms
(vaginal).
