Printed on 2/14/2026
For informational purposes only. This is not medical advice.
The Neonatal Bilirubin Risk calculator plots a newborn's total serum bilirubin (TSB) against their age in hours on the Bhutani nomogram to determine risk zone for subsequent significant hyperbilirubinemia. Risk zones are: Low Risk (<40th percentile), Low-Intermediate (40th–75th), High-Intermediate (75th–95th), and High Risk (≥95th percentile). This guides follow-up timing and phototherapy decisions. The AAP recommends universal bilirubin screening before discharge and risk-based follow-up. Failure to identify and treat severe neonatal jaundice can lead to kernicterus (bilirubin encephalopathy).
Formula: Hour-specific bilirubin percentile thresholds (Bhutani nomogram, 1999).
Your newborn's bilirubin level is plotted against their age in hours to determine the risk zone on the Bhutani nomogram. The Low Risk zone (below the 40th percentile) indicates a very low likelihood of subsequent significant hyperbilirubinemia. The Low-Intermediate zone (40th-75th percentile) carries a small but real risk. The High-Intermediate zone (75th-95th percentile) indicates moderate risk and warrants close follow-up within 24-48 hours. The High Risk zone (above the 95th percentile) indicates significant risk and usually requires immediate evaluation for phototherapy.
The risk zone helps determine how soon after discharge the infant needs a follow-up bilirubin check. High-risk zone infants may need follow-up within 24 hours or may require phototherapy before discharge. Low-risk zone infants may safely have follow-up in 48-72 hours. These timelines should be adjusted based on additional risk factors such as prematurity, hemolysis, and breastfeeding status.
Use this tool for all newborns as part of the universal pre-discharge bilirubin screening recommended by the American Academy of Pediatrics (AAP). It is most commonly applied at 24-72 hours of life when a total serum bilirubin or transcutaneous bilirubin measurement is obtained. It is especially important for infants being discharged before 72 hours of age, as bilirubin levels typically peak at 3-5 days of life.
This tool is also useful at follow-up visits in the first week of life to reassess bilirubin trajectory and determine whether phototherapy thresholds are being approached.
The Bhutani nomogram was developed from a specific population of healthy term and near-term newborns (gestational age 36 weeks or greater) and may not be directly applicable to premature infants below 35 weeks gestational age, who have lower phototherapy thresholds. The nomogram predicts the risk of subsequent hyperbilirubinemia but does not itself determine phototherapy thresholds — the AAP phototherapy guidelines are a separate tool.
A single bilirubin measurement in the low-risk zone does not guarantee the infant will not develop significant jaundice, particularly if risk factors are present (ABO incompatibility, G6PD deficiency, significant bruising, poor feeding). Clinical judgment and appropriate follow-up remain essential regardless of the risk zone result.
For related assessments, see Apgar Score, Pediatric Weight Estimate and Pediatric GCS.
Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.
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