OBJECTIVETo plot a hour-specific transcutaneous bilirubin (TCB) nomogram for healthy neonates, and to evaluate its value for prediction of the risk of neonatal hyperbilirubinemia.

METHODSA total of 5,250 healthy full-term or near-term neonates (gestational age≥35 weeks, birth weight≥2 000 g) were enrolled as subjects. Their TCB values were continuously recorded for 168 hours after birth. The TCB values in the high-risk zones of three time periods, 24-48, 49-72, and 73-96 hours after birth, were used as predictors. The hour-specific TCB nomogram combined with the receiver operating characteristic (ROC) curve was used to evaluate the predictive value of hour-specific TCB nomogram for hyperbilirubinemia.

RESULTSAccording to the hour-specific TCB nomogram, the TCB value dramatically increased during 16-72 hours after birth, and the increase slowed down gradually during 72-144 hours. Finally, the curve reached a plateau after 144 hours. Particularly, the P95 of TCB had been stabilized at 96 hours. The P40, P75, and P95 peak values of TCB were 173, 217, and 248 µmol/L, respectively. For the prediction of hyperbilirubinemia, the areas under the ROC curve of TCB at 24-48, 49-72, and 73-96 hours after birth were 0.77, 0.85, and 0.87, respectively. The high-risk zones at 24-48, 49-72, and 73-96 hours after birth predicted the incidence rates of neonatal hyperbilirubinemia as 35.03%, 43.35%, and 79.95%, respectively, with positive likelihood ratios of 3.35, 4.75, and 22.70, respectively.

CONCLUSIONSThe hour-specific TCB nomogram and the division of TCB risk zones can give a satisfactory prediction of the incidence of neonatal hyperbilirubinemia. The neonate with a bilirubin level in the high-risk zone within 73-96 hours after birth is likely to have hyperbilirubinemia after 73-96 hours.