Misoprostol is part of the standard method of medical abortion for terminating early pregnancies. First the patient is given an oral dose of mifepristone (you might recognize it under a different name, RU-486), which blocks the action of the hormone progesterone needed to sustain pregnancy. A couple of days later, after the embryo has detached from the uterine wall as a result, an oral dose of misoprostol is given. This stimulates the uterus to contract and expel its now-lifeless contents. Misoprostol does not work well as an abortifacient on its own, however, since the contractions it provokes can lead to uterine tearing. This is an unreliable and dangerous way to terminate a pregnancy.