Poa 39+5. Born on 1st june, 2026, 10 am. Today 4th june, 10am. Total serum

Clinical answer with reasoning, red flags and references. Clinically reviewed by Dr Kola Tytler MBBS CertHE MBA MRCGP.

Posted: 4 June 2026Updated: 4 June 2026 Clinically Reviewed
Dr Kola Tytler MBBS CertHE MBA MRCGPClinical Lead • iatroX

Does this newborn require phototherapy?

The newborn is 3 days old (72 hours) at the time of bilirubin measurement, at a gestational age of 39 weeks and 5 days, which classifies as term (≥38 weeks) . The total serum bilirubin level of 18.3 mg/dL converts to approximately 313 micromol/L (1 mg/dL = 17.1 micromol/L), which is a significant hyperbilirubinaemia level . According to the NICE CG98 threshold table for babies ≥38 weeks and at 72 hours (36-78 hours), phototherapy is recommended if the bilirubin level exceeds approximately 225 to 312 micromol/L depending on exact age in hours . Specifically, the phototherapy threshold at 72 hours is around 300 micromol/L . Since 313 micromol/L slightly exceeds the phototherapy threshold at 72 hours, phototherapy should be started .

How many boxes above the phototherapy line in the bilirubin nomogram does this level correspond to?

The bilirubin nomogram used in NICE CG98 has threshold levels marked in increments roughly corresponding to 50 micromol/L steps above or below lines for phototherapy and exchange transfusion . The newborn's level of 313 micromol/L is just above the phototherapy threshold line at 300 micromol/L for 72 hours of age, corresponding roughly to one box above the phototherapy threshold line in the bilirubin nomogram .

Therefore, this newborn requires phototherapy, with the bilirubin level approximately one box above the phototherapy threshold on the nomogram .

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