Kidney diseases / Ultrasound / Prospective studies / Humans / Ultrasonography / Female / Male / Pediatric radiology / Infant / ROC Curve / Newborn Infant / Diagnostic Accuracy / Area Under the Curve / Postnatal Care / Prospective Study / Predictive value of tests / Female / Male / Pediatric radiology / Infant / ROC Curve / Newborn Infant / Diagnostic Accuracy / Area Under the Curve / Postnatal Care / Prospective Study / Predictive value of tests