Which blood group system is significant in hemolytic disease of the newborn?

The Rh blood group system is significant in hemolytic disease of the newborn (HDN) due to the potential for Rh incompatibility between the mother and her fetus. This situation often arises when an Rh-negative mother is pregnant with an Rh-positive fetus, which can occur if the father of the baby is Rh-positive. If fetal red blood cells enter the maternal circulation, typically during delivery, the mother may produce antibodies against the Rh antigen. In subsequent pregnancies, if the mother becomes pregnant again with another Rh-positive fetus, these pre-formed antibodies can cross the placenta and attack the fetal red blood cells, leading to hemolysis. This can result in significant complications for the infant, including anemia, jaundice, and in severe cases, hydrops fetalis or death.

While the ABO blood group system can also cause hemolytic disease of the newborn, it is generally less severe than Rh incompatibility. The Lewis and MN blood group systems do not have the same clinical implications for hemolytic disease of the newborn, as they are not typically involved in maternal-fetal blood group incompatibility that leads to the immune response observed in HDN. Thus, the Rh blood group system holds particular importance in the context of hemolytic disease of the