Termination of early pregnancy by a single dose of mifepristone (RU 486), a progesterone antagonist.

Mifepristone (RU 486) is a new steroid which is a progesterone antagonist and which is able to interrupt early pregnancy without any major side-effects. The purpose of our study was to evaluate the clinical effect of a single oral dose of 600 mg on early pregnancy. The study included 150 healthy women applying for a legal abortion with an amenorrhea of no more than 42 days. Pregnancy was confirmed by clinical and ultrasound examination and plasma HCG assessment. Success was assumed by repeating these exams on the eighth day. 131 patients had a complete abortion (87.3%), with a very few side-effects. Only two patients needed curettage for heavy bleeding. Mifepristone is able to terminate early pregnancy by an easy ambulatory method under medical supervision.