RHD and fetal erythroblastosis: Among all the erythrocyte alloantigens, the one with the greatest clinicalsignificance and the greatest number of publications is anti-Rhesus (Rh)D.(1) However, amid the 345red blood cells antigens listed by the International Society of Blood Transfusion,more than 50 may be associated with the occurrence of HDFN.(3) Among them are other antibodiesagainst the Rh system in addition to RhD, and also against other blood group systemssuch as ABO, Kell, Duffy, Kidd, MNS, and others.(4)