Cord blood bilirubin and prediction of neonatal hyperbilirubinemia and perinatal infection in newborns at risk of hemolysis.

OBJECTIVE: To assess the accuracy of umbilical cord bilirubin values to predict jaundice in the first 48h of life and neonatal infection. METHOD: Newborn infants treated at a regional well-baby nursery born at ≥36 weeks of gestation were included in this retrospective cohort study. All infants born in a 3-year period from mothers with O blood type and/or Rh-negative were included and had the umbilical cord bilirubin levels measured. Hyperbilirubinemia in the first 48h was defined as bilirubin levels above the phototherapy threshold. Neonatal infection was defined as any antibiotic treatment before discharge. RESULTS: A total of 1360 newborn infants were included. Two hundred and three (14.9%) newborn infants developed hyperbilirubinemia in the first 48h of life. Hyperbilirubinemic infants had smaller birth weight, higher levels of umbilical cord bilirubin, a higher rate of infection and were more often direct antiglobulin test positive. Umbilical cord bilirubin had a sensitivity of 76.85% and a specificity of 69.58% in detecting hyperbilirubinemia in the first 48h, with the cut-off value at 34µmol/L. The area under the receiver operating characteristic curve was 0.80 (95% CI: 0.78-0.82). Umbilical cord bilirubin had a sensitivity of 27.03% and specificity of 91.31% in detecting perinatal infection. The area under the receiver operating characteristic (ROC) curve was 0.59 (95% CI: 0.57-0.63). CONCLUSIONS: A positive correlation was found between umbilical cord bilirubin and hyperbilirubinemia in the first 48h of life. Umbilical cord bilirubin is a poor marker for predicting neonatal infection.