How does medication abortion work?

Procedure	Mechanism of Action	Advantages	Disadvantages
Mifepristone/ Misoprostol	Mifepristone is taken orally and blocks the action of progesterone. This results in: Uteral lining thinning Pregnancy detachment Cervical softening and dilation Uterine contractions Subsequent administration of oral or vaginal misoprostol, a prostaglandin E analogue, results in uterine contractions and expulsion of the products of conception.	High success rate (95%) Available during early pregnancy Resembles a "natural miscarriage" Often considered to be more "private" Usually avoids surgical intervention Anesthesia not usually required	Requires at least two clinic visits Takes days, sometimes weeks, to complete Efficacy decreases at later gestational ages Post-procedure bleeding may last for weeks Women may see blood clots and the products of conception Mifepristone is not available in most countries Mifepristone can be expensive
Methotrexate/ Misoprostol	Methotrexate is anti-metabolite that inhibits DNA synthesis. Given by injection or taken orally, methotrexate interferes with the implantation process. Subsequent administration of oral or vaginal misoprostol, a prostaglandin E analogue, results in uterine contractions and expulsion of the products of conception.	High success rate (95%) Used during early pregnancy Resembles a "natural miscarriage" Often considered to be more "private" Usually avoids aspiration intervention Anesthesia not usually required Treats ectopic pregnancy	Requires at least two clinic visits Takes days to weeks to complete (longer than the mifepristone regimen) Post-procedure bleeding may last for weeks Efficacy decreases after 7 weeks gestation Women may see blood clots and the products of conception Methotrexate is not available in all countries
Misoprostol Only	Serial administration of oral or vaginal misoprostol, a prostaglandin E1 analogue, results in uterine contractions and expulsion of the products of conception.	Used during early pregnancy Resembles a "natural miscarriage" Often considered to be more "private" Usually avoids aspiration intervention Anesthesia not usually required More accessible and affordable than other medical abortion regimens, particularly in developing countries	Success rate is relatively low and variable (65%-93%) Regimen is still currently under investigation Takes days to weeks to complete Post-procedure bleeding my last for weeks Women may see blood clots and the products of conception
Vacuum Aspiration (Surgical Abortion)	A straw-like tube (a cannula), which is attached to a suction apparatus is inserted into the uterus through the open (dilated) cervix. The uterine contents are then emptied by suction.	High success rate (99%) May requires only one clinic visit Procedure completed within minutes Sedation is available	Involves an invasive procedure May not be available very early in pregnancy Often considered to be less "private"