In their early studies on icterus neonatorum Ylppö1 and Hirsch2 pointed out that bilirubin is usually present in increased amounts in cord blood. Subsequent investigators3 have confirmed these observations. Ylppö also presented data showing that the intensity of the subsequent icterus—and the presence of visible jaundice—could be predicted from the height of the icteric index in cord blood. It is noteworthy that this observation of hyperbilirubinemia at birth has not been generally appreciated by pediatricians or obstetricians. Icterus neonatorum is generally assumed to develop only after birth, as a result of changes in the neonatal period. A theory on the origin of icterus neonatorum was proposed by Schick4 in 1921. He stated the belief that the fetal placenta played an important part in the breaking up of maternal hemoglobin during the latter months of pregnancy in order to make iron available for the creation of fetal