Abortion is the most common complication of human gestation, occurring in at least 75% of all women trying to become pregnant, and most of these losses are unrecognized and occur before or during the next expected menses. There are two types of abortion, the induced and spontaneous abortion (miscarriage). There are seven types of spontaneous abortion are present. Recurrent abortion (medically termed habitual abortion) is defines as three or more successive spontaneous abortions. Miscarriages can occur for many reasons, not all of which can be identified. About 50% of cases have no cause and are classified as idiopathic. This book provides information regarding incidence of viral and parasitic diseases, whether the patients had diabetes mellitus, as well as the immunological changes that associated with single and recurrent abortion as the main causes associated with abortion in Iraqi women.