The following medical terms are used to categorize abortion:
Spontaneous abortion (miscarriage): An abortion due to accidental trauma or natural causes. Most miscarriages are due to incorrect replication of chromosomes; they can also be caused by environmental factors.
Induced abortion: Abortion that has been caused by deliberate human action. Induced abortions are further subcategorized into therapeutic and elective:
To save the life of the pregnant woman.
To terminate pregnancy that would result in a child born with a congenital disorder that would be fatal or associated with significant morbidity.
To selectively reduce the number of fetuses to lessen health risks associated with multiple pregnancy.
Elective abortion: Abortion performed for any other reason.
In common parlance, the term "abortion" is synonymous with induced abortion. However, in medical texts, the word 'abortion' might exclusively refer to, or may also refer to, spontaneous abortion (miscarriage).