The Columbia Encyclopedia, Sixth Edition. Columbia Encyclopedia World Factbook American Heritage Coll. Any interruption of human pregnancy prior to the 28th week is known as abortion. The term spontaneous abortion, or miscarriage, is used to signify delivery of a nonviable embryo or fetus due to fetal or maternal factors, as opposed to purposely induced abortion.
Therapeutic abortion is an induced abortion performed to preserve the health or life of the mother.
Immunological reactions, in which maternal antibodies mistake the fetus for foreign tissue, have been implicated in recurrent, or habitual spontaneous abortions. Most occur in the first two weeks after conception, and in many cases the mother is not aware of the pregnancy. 2 Induced Abortion Abortion can be induced for medical reasons or because of an elective decision to end the pregnancy. It is used within the first seven weeks of pregnancy. A second drug is taken two days later to start uterine contractions and complete the abortion.