Hemolytic disease of the newborn (HDN) is primarily associated with the Rh factor, specifically when an Rh-negative mother carries an Rh-positive fetus. In this condition, if fetal red blood cells, which possess the Rh antigen, enter the maternal circulation, the mother's immune system may recognize them as foreign and produce antibodies against them. These antibodies can cross the placenta and attack the fetal red blood cells, leading to hemolysis and resulting in anemia, jaundice, and potentially severe complications for the newborn.
Therefore, the risk of HDN is notably higher in Rh-negative mothers. The presence or absence of the Rh factor is crucial in this context; mothers with blood types lacking the Rh antigen are at risk of sensitization if they have an Rh-positive child, which directly contributes to the development of hemolytic disease.
In contrast, blood types A+, O-, and B+ do not have the same association with hemolytic disease of the newborn, as they do not present the same risk factors related to maternal-fetal Rh incompatibility.