Alloimmunisation via previous transfusion places female Kpb-negative recipients at risk for having children with clinically significant hemolytic disease of the newborn.

We report a case of clinically significant hemolytic disease of the newborn due to Kpb alloimmunisation requiring obstetric intervention. This case and a review of the literature are in contrast to reviews of hemolytic disease of the newborn that either ascribe no significance to the Kpb antigen or suggest that it causes only rare or mild disease. Analysis of our Kpb-negative donor pool suggests that prior transfusion greatly increases the chance of alloimmunisation. The role of frozen rare donor registry cells as a public resource is emphasised.