A condition characterized by the abnormal presence of erythroblasts in the circulation of the fetus or NEWBORNS. It is a disorder due to blood group incompatibility, such as the maternal alloimmunization by fetal antigen RH FACTORS leading to hemolysis of erythrocytes, hemolytic anemia (anemia, hemolytic), general edema (hydrops fetalis), and SEVERE jaundice IN NEWBORN.