How does mifeprex work for abortions?

Mifeprex action: Mifepristone is a synthetic steroid. It binds to Progesterone receptors (uterus) blocking the effects of progesterone. Progesterone is needed for continuation of pregnancy. When used for the termination of pregnancy, this leads to contraction-inducing activity in the uterine muscle, greater sensitivity to prostaglandins(other medication) and damage to vessels supporting the pregnancy.