Complications of HDN could include kernicterus, hepatosplenomegaly, inspissated (thickened or dried) bile syndrome and/or greenish staining of the teeth, hemolytic anemia and damage to the liver due to excess bilirubin. Conditions that may cause similar symptoms in the newborn period include: acquired hemolytic anemia, congenital toxoplasma, congenital syphilis infection, congenital obstruction of the bile duct, and cytomegalovirus (CMV) infection. High at birth or rapidly rising bilirubin Prolonged hyperbilirubinemia Bilirubin Induced Neurological Dysfunction Cerebral Palsy Kernicterus Neutropenia Thrombocytopenia Hemolytic anemia – must not be treated with iron Late onset anemia – must not be treated with iron. Can persist up to 12 weeks after birth. Pathophysiology Antibodies are produced when the body is exposed to an antigen foreign to the make-up of the body. If a mother is exposed to a foreign antigen and produces IgG (as opposed to IgM which does not cross the placenta), the IgG will target the antigen, if present in the fetus, and may affect it in utero and persist after delivery. The three most common models in which a woman becomes sensitized toward (i.e., produces IgG antibodies against) a particular antigen are hemorrhage, blood transfusion, and ABO incompatibility. Fetal-maternal hemorrhage, which is the movement of fetal blood cells across the placenta, can occur during abortion, ectopic pregnancy, childbirth, ruptures in the placenta during pregnancy (often caused by trauma), or medical procedures carried out during pregnancy that breach the uterine wall. In subsequent pregnancies, if there is a similar incompatibility in the fetus, these antibodies are then able to cross the placenta into the fetal bloodstream to attach to the red blood cells and cause their destruction (hemolysis). This is a major cause of HDN, because 75% of pregnancies result in some contact between fetal and maternal blood, and 15–50% of pregnancies have hemorrhages with the potential for immune sensitization. The amount of fetal blood needed to cause maternal sensitization depends on the individual's immune system and ranges from 0.1 mL to 30 mL. The woman may have received a therapeutic blood transfusion. ABO blood group system and the D antigen of the Rhesus (Rh) blood group system typing are routine prior to transfusion. Suggestions have been made that women of child-bearing age or young girls should not be given a transfusion with Rhc-positive blood or Kell1-positive blood to avoid possible sensitization, but this would strain the resources of blood transfusion services, and it is currently