RHCE and anemia (phenotype): The severity is reflected by HDFN treatments, including neonatal phototherapy for jaundice, simple transfusions for neonatal anemia, and exchange transfusions of IVIG for risk of kernicterus.3, 4, 5 Top-off (simple) transfusions and exchange transfusions or IVIG treatment were approximately 10-fold and 4-fold lower, respectively, among newborns with ABO-induced HDFN than among newborns with Rh-induced or non-Rh–induced HDFN, consistent with the known risks in these groups.5