What is the normal bilirubin level in infants?

Normal bilirubin levels in infants vary depending on age and time since birth. In full-term newborns, serum bilirubin levels typically do not exceed 6 mg/dL within the first 24 hours, 9 mg/dL within 48 hours, and 12.9 mg/dL after 72 hours; jaundice usually resolves spontaneously within two weeks. In preterm infants, normal bilirubin levels are relatively higher: up to 7 mg/dL within the first 24 hours, 12 mg/dL within 48 hours, and 15 mg/dL after 72 hours; jaundice may persist for up to four weeks. These values reflect the physiological range of neonatal jaundice. Bilirubin levels exceeding these thresholds—or prolonged jaundice beyond the expected timeframe—may indicate pathological jaundice, warranting prompt medical evaluation and treatment.