Transcutaneous bilirubin levels in the first 96 hours in a normal newborn population of > or = 35 weeks' gestation.

OBJECTIVE: To obtain transcutaneous bilirubin (TcB) measurements, at 6-hour intervals, in the first 96 hours after birth in a normal newborn population (gestational age: > or =35 weeks).

METHODS: We performed 9397 TcB measurements on 3984 healthy newborn infants (gestational age: > or =35 weeks) from 6 to 96 hours of age. All measurements were performed in the well-infant nursery with a Draeger Air-Shields transcutaneous jaundice meter (model JM-103), within 2 hours of the designated time.

RESULTS: There was a distinct pattern to the velocity of the increase in TcB levels over different time periods. TcB levels increased in a linear manner most rapidly in the first 6 to 18 hours and then less rapidly from 18 to 42 hours, followed by a much slower increase until peak levels occurred. Decreasing gestational age was associated significantly with higher TcB levels.

CONCLUSIONS: We provide data on neonatal bilirubinemia, based on TcB levels determined in a large, predominately white and breastfed, North American population. Infants who require closer evaluation and observation initially are those whose bilirubin levels are > or =95th percentile, ie, increasing more rapidly than 0.22 mg/dL per hour in the first 24 hours, 0.15 mg/dL per hour between 24 and 48 hours, and 0.06 mg/dL per hour after 48 hours. These data should be useful for detecting aberrant trends, identifying infants who need additional evaluation, and planning appropriate follow-up for jaundiced newborns.