Pregnancy and D antigen

The D antigen is part of the Rh antigen system, and antibodies against it can cause hemolytic transfusion reactions or hemolytic disease of the fetus and newborn (HDFN). Anti-D antibodies usually develop after transfusion of D-positive RBCs, during pregnancy with a D-positive conceptus, or are detected following recent administration of anti-D antibodies (RhoGAM). The anti-D antibodies present in this patient’s plasma likely represent passive immunization by RhoGAM.