Neonatal Bilirubin Calculator

Neonatal jaundice (hyperbilirubinemia) is the most common condition requiring medical evaluation in newborns. About 60% of term and 80% of preterm babies develop jaundice in the first week. Most cases are benign physiologic jaundice; a small fraction can progress to bilirubin-induced neurological dysfunction if untreated.

The American Academy of Pediatrics (AAP 2004) guidelines provide phototherapy thresholds based on total serum bilirubin, postnatal age in hours, gestational age, and neurotoxicity risk factors. Risk factors include isoimmune hemolytic disease, G6PD deficiency, asphyxia, significant lethargy, temperature instability, sepsis, metabolic acidosis, and serum albumin below 3 g/dL.

Phototherapy thresholds for infants 35+ weeks gestation:

Postnatal age | Low risk | Medium risk | High risk 24 hours | 12 mg/dL | 10 mg/dL | 8 mg/dL 48 hours | 15 mg/dL | 13 mg/dL | 11 mg/dL 72 hours | 18 mg/dL | 15 mg/dL | 13 mg/dL Over 72 hours | 20 mg/dL | 17 mg/dL | 15 mg/dL

Bilirubin rises naturally over the first 3-5 days before the liver’s conjugation capacity catches up. A level above threshold does not by itself mean something is wrong with the baby — it means the rate or height of rise warrants action before it can cause harm.

Exchange transfusion thresholds are typically 5 mg/dL above phototherapy thresholds. If the level is within 2-3 mg/dL of the phototherapy threshold, repeat measurement is usually recommended within 4-8 hours.

This tool is for educational and informational purposes. Clinical decisions for newborns require direct physician evaluation and the full clinical context.