AbstractBackground: The evidence from individual studies to support the maturational pattern of glomerular filtration rate (GFR) in healthy term-born neonates is inconclusive. We performed an individual participant data (IPD) meta-analysis of reported measured GFR (mGFR) data aimed to establish GFR reference values in the first month of life. As a secondary objective, we aimed to optimize neonatal creatinine-based GFR estimations in clinical care.Methods: We identified studies reporting mGFR measured by exogenous markers or creatinine clearance (CrCL) in healthy term-born neonates through searching the Pubmed and ClinicalTrials.gov databases. The relationship between postnatal age and individual clearance was investigated using cubic splines with generalized additive linear mixed models. From our reference values, we estimated an updated coefficient for the Schwartz equation (eGFR(ml/min/1.73m2)=(k*height (cm))/serum creatinine(mg/dl)).Results: Fifty out of 1521 screened articles reported mGFR in healthy term-born neonates, and we analyzed 1041 mGFR values from 944 neonates. IPD were available for 367 neonates and the other 577 neonates were represented by 44 aggregated data points as means/medians per cohortgroup. GFR doubled in the first five days after birth from 19.6 (95% CI 14.7;24.6) ml/min/1.73m2 to 40.6 (95% CI 36.7;44.5) ml/min/1.73m2, then more gradually increased to 59.4 (95% CI 45.9;72.9) ml/min/1.73m2 by four weeks of age. A coefficient of 0.31 to estimate GFR best fitted the data.Conclusions: These reference values for healthy term newborns show a biphasic increase in GFR with the largest increase between days 1 and 5. Our mGFR reference values and updated coefficient for the Schwartz equation can help identify acute kidney injury or augmented renal clearance altered GFR in term-born neonates.