A nurse is caring for a client who has just delivered her first newborn. The nurse anticipates hyperbilirubinemia due to Rh incompatibility. The nurse should understand that hyperbilirubinemia occurs with Rh incompatibility for which of the following reasons?

Choice A rationale Anti-A and anti-B antibodies are typically of the IgM class, which generally do not cross the placental barrier effectively due to their large molecular size. Therefore, these antibodies are not the primary cause of hemolytic disease of the newborn in Rh incompatibility. ABO incompatibility involves different antibody mechanisms and usually results in less severe hemolysis compared to Rh incompatibility. Choice B rationale If the client's blood contains the Rh factor (Rh-positive) and the newborn's does not (Rh-negative), sensitization and antibody formation in the fetus typically do not occur. The issue arises when the mother is Rh-negative and the fetus is Rh-positive, leading to maternal antibody production against fetal Rh antigens. Choice C rationale In Rh incompatibility, an Rh-negative client exposed to Rh-positive fetal blood during pregnancy or delivery produces anti-Rh (IgG) antibodies. These smaller IgG antibodies can readily cross the placental barrier into the fetal circulation, where they bind to and destroy fetal Rh-positive red blood cells, leading to hemolytic anemia and subsequent hyperbilirubinemia due to increased heme breakdown. Choice D rationale A history of receiving a transfusion with Rh-negative blood would not typically lead to Rh incompatibility with an Rh-positive fetus. In fact, receiving Rh-negative blood when one is Rh-negative would be a compatible transfusion and would not induce anti-Rh antibody production. The problem arises from exposure to Rh-positive blood.