Rate of rise of total serum bilirubin in very low birth weight preterm infants.

BACKGROUND: To assess the postnatal rate of rise (ROR) of total serum bilirubin (TSB) in very low birth weight (VLBW) preterm infants, to determine risk factors associated with a rapid rise (>90th percentile), and to compare ROR and hour-specific TSB at postnatal 12-48 h with data of term infants retrieved from the literature.

METHODS: Retrospective analysis of 2430 routine TSB concentrations obtained between birth and initiation of phototherapy in 483 VLBW infants.

RESULTS: TSB increased by a median (interquartile range) ROR of 0.15 (0.11-0.19) mg/dL/h. The 50th percentile of TSB was below the 40th percentile of (near-)term counterparts at 12-48 h. TSB ROR correlated with the age at initiation (RS  = -0.687; p < 0.001) and the duration (RS  = 0.444; p < 0.001) of phototherapy. ROR >90th percentile (>0.25 mg/dL/h) was associated with lower gestational ages [27.2 (25.4-29.3) vs. 28.4 (26.4-30.4) weeks], lower birth weights [978 (665-1120) vs. 1045 (814-1300) g], and lower 5-min Apgar scores [7 (7-8) vs. 8 (7-9)].

CONCLUSION: ROR of TSB is an indicator for early and prolonged phototherapy. While hour-specific TSB and ROR at 12-48 h are lower than those reported for (near-)term infants, TSB appears to rise more rapidly in infants with low gestational age, low birth weight, and low 5-min Apgar score.