Perinatal risk factors of renal outcome in former extremely low birth weight neonates

Former Extremely Low Birthweight (ELBW) neonates suffer from adverse renal and cardiovascular outcomes later in life. Less is known about additional perinatal risk factors for these adverse outcomes which we have investigated in this study. We compared renal outcome between ELBW children and controls, to find perinatal risk factors for poorer renal outcome and to unveil associations between kidney function and blood pressure. This study included 93 former ELBW children and 87 healthy controls with a mean age of 11 years at assessment. We measured cystatin C-based estimated glomerular filtration rate (eGFR) and blood pressure. Blood pressure and eGFR levels were compared between cases and controls. We subsequently investigated perinatal risk factors for adverse outcome amongst ELBW children. ELBW children have significantly higher blood pressure (mean SBP percentile 75^th vs. 47^th, p <0.001) and lower mean eGFR (94 vs. 107 ml/min/1.73 m², p = 0.005) compared to the control group. Elevated blood pressure did not correlate with perinatal characteristics and none of them had microalbuminuria. ELBW children with eGFR <90 ml/min/1.73 m² were ventilated longer (17 vs. 9 days, p = 0.006), more frequently male (OR = 3.33, p = 0.055) and tended to suffer more from intraventricular hemorrhage (40% vs. 15.8%, p = 0.056). There was no association between blood pressure and kidney dysfunction.

Understanding risk profiles for unfavorable outcomes may help to identify children at increased risk for kidney dysfunction. Poorer eGFR was associated with longer ventilation, male sex, and intra-ventricular hemorrhage but not with blood pressure. This knowledge can lead to safer neonatal therapeutic regimens for ELBW infants, a more intensive follow-up and earlier treatment initiation for children at highest risk.

• Extremely Low Birthweight (ELBW) neonates suffer later in life from adverse renal and cardiovascular outcomes. • Perinatal risk factors that further predict the individual risk for adverse outcomes are not well known.

• Poorer eGFR in adolescence was associated with male sex, longer ventilation and intra-ventricular hemorrhage at birth but not with blood pressure. • Former ELBW infants had higher blood pressures compared to controls, but no microalbuminuria. • This knowledge can lead to potential precision medicine, safer neonatal therapeutic regimens for ELBW infants, a more intensive follow-up and earlier treatment initiation for children at highest risk.