Miscarriage describes the natural or accidental termination of a pregnancy at a stage where the fetus is incapable of surviving. The medical term for Miscarriage is "spontaneous abortion," Miscarriages can occur for many reasons, not all of which can be identified. While miscarriage can result from physical trauma, like exposure to certain chemicals, diseases, or physical blows, they are rarely the cause. A miscarriage usually results from biological defects in the mother or genetic defects in the developing fetus.