IT IS GENERALLY agreed that hemolytic disease of the newborn is usually caused by antibodies formed in Rhesus-negative mothers against the Rh factor D (Rh0) of Rhesus-positive children. According to Wallerstein1 this mechanism accounts for 92%, according to Mollison2 for some 95%, of all cases of the disease. Of the remaining instances, a few are due to sensitization of the mother against one of the other Rh antigens or against an antigen belonging to a different blood group system such as Kell. This still leaves a residue of unexplained cases, and in many of these incompatibility of the major ABO blood groups has been held responsible.
By now a considerable number of instances of the disease attributed to maternal anti-A or anti-B antibodies has been recorded all over the world. In 1948, Grumbach and Gasser3 fully reviewed the literature of the subject and added nine cases