Which antigen system's antibodies do not cause hemolytic disease of the fetus and newborn?

The Lewis antigen system is unique among blood group systems because its antibodies are not typically associated with hemolytic disease of the fetus and newborn (HDFN). The Lewis antigens are carried on glycoproteins found in body fluids rather than on red blood cells, and the antibodies produced against them usually do not cross the placenta. As a result, Lewis antibodies are generally considered non-reactive in the context of fetal blood, meaning that they do not lead to the destruction of fetal red blood cells.

In contrast, antibodies associated with other antigen systems, such as Kell, Duffy, and Rh, can cross the placenta and have the potential to cause HDFN by attacking fetal red blood cells that express these antigens. Specifically, D and Kell antigens have well-documented cases of causing severe hemolytic reactions and complications in newborns if the mother possesses antibodies against them. Therefore, understanding the role of the Lewis system in regard to fetal health is crucial for medical technologists, particularly in transfusion medicine and prenatal care.