Supplementary Material for: Urinary output of very low birth weight infants during the first weeks of life

Introduction:
Daily urinary output (UOP) serves as important tool to identify acute kidney injury (AKI) in preterm infants. However, reference values for UOP, especially stratified for gestational age, are missing.

Methods:
This retrospective single-center study assessed UOP during the first 28 days of life in 128 very low birth weight (VLBW) infants.

Results:
VLBW infants exhibit a highly dynamic daily UOP profile in the first 28 days of life with a maximum at day 12 with 4.78 ml/kg bodyweight/h. In the subcohort of 64 extremely low gestational age neonates (ELGAN), the highest UOP is measured during the second week of life. Infants born before 24 weeks of gestation have significantly higher UOP than more mature infants.

Conclusion:
UOP is dynamic in the postnatal period and differs significantly between gestational age cohorts in the subgroup of ELGANs. These data might point to an adaption of the UOP threshold for neonatal AKI in preterm infants.