(HDN) (hē'mō-lit'ik di-zēz' nū'bōrn) Erythroblastosis fetalis due to maternal-fetal incompatibility with respect to an antigen of the ABO blood group; the fetus possesses A or B antigen that is lacking in the mother, and the mother produces immune antibody that causes hemolysis of fetal erythrocytes. Synonym(s): ABO haemolytic disease of the newborn.