Abortion is the termination of a pregnancy before the time of extrauterine viability. An abortion terminates the life of the embryo (the fertilized egg before three months of growth) or the fetus (after three months). Spontaneous abortions, also called miscarriages, occur when the fetus or embryo is spontaneously expelled by the body. An induced abortion occurs when there is deliberate human intervention to end the pregnancy. Induced abortions can be accomplished medically or surgically.

Medically induced abortions are accomplished by giving drugs like mifepristone (RU-486), which block the work of the hormone progesterone and soften the lining of the uterus, thus ending the pregnancy. Medically induced abortions can generally only be used if the woman is less than seven weeks from her last menstrual period. Mifepristone is administered in conjunction with another medicine called misoprostol, which causes the...