Hemolytic disease of newborn (hdn/hdfn) is caused due to antibody formed by the mother which crosses the placenta and causes lysis of fetal red blood cells which are positive for a particular Rh antigen but absent in the mother..This hemolysis causes anemia and hyperbilirubinemia in the fetus..But the first pregnancy is not affected..Thus it is important to test and detect this complication in subsequent pregnancies..
