RESUMO
The postnatal rate of rise of the undirect bilirubin concentration was compared with cord hematocrit and bilirubin values in 44 newborn infants with Rh isoimmune hemolytic disease. Cord blood values failed to predict the severity of hyperbilirubinemia with sufficient accuracy to warrant their use as therapeutic guidelines. A statistically significant positive correlation was found between the cord serum indirect bilirubin concentration and its subsequent rise in 19 infants who had received antenatal phenobarbital therapy, but this relationship was not observed in untreated infants. The phenobarbital-treated infants had a slower postnatal rise of indirect bilirubin than did nontreated controls. There was no reliable indicator of the severity of hyperbilirubinemia other than careful monitoring of the serum bilirubin concentration during the early hours of life.