Hyperbilirubinemia, neonatal: Elevation of the bilirubin level in the blood of the newborn, which results in yellowish staining of the skin and whites of the newborn's eyes (sclerae) by pigment of bile (bilirubin). In newborn babies a degree of jaundice is normal. It is due to the breakdown of red blood cells (which release bilirubin into the blood) and to the immaturity of the newborn's liver (which cannot effectively metabolize the bilirubin and prepare it for excretion into the urine). Normal neonatal jaundice typically appears between the 2nd and 5th days of life and clears with time.
Neonatal hyperbilirubinemia is also referred to as neonatal jaundice and physiologic jaundice of the newborn.