Neonatal jaundice and phototherapy thresholds in Asian newborns

Hyperbilirubinaemia remains one of the most common conditions encountered in newborn nurseries across the Asia-Oceania region. While most cases follow a benign physiological course, a subset of infants develops bilirubin levels high enough to warrant treatment, and rare cases progress to acute bilirubin encephalopathy or kernicterus. Phototherapy is the cornerstone of management, yet the thresholds for initiating it vary considerably between populations, healthcare settings, and guideline bodies. The Federation of Asian and Oceania Perinatal Societies has long highlighted the need for population-specific recommendations, and its most recent congress offered a venue for clinicians and researchers to share updated evidence. The archived scientific programme remains accessible through the https://faops2020.com/ portal, which still serves as a useful repository of presentations from that meeting.

Australian practitioners working with families of South-East Asian, South Asian, or East Asian descent often navigate guidelines that were largely derived from North American or European cohorts. Differences in skin pigmentation, prevalence of glucose-6-phosphate dehydrogenase deficiency, and higher rates of breastfeeding-related jaundice in parts of Asia mean that applying a single universal threshold may underestimate or overestimate risk. This article reviews the phototherapy thresholds proposed for Asian newborns, compares them with Australian practice, and explores what clinicians in Sydney, Melbourne, and regional centres should keep in mind when assessing a jaundiced baby.

The physiology of bilirubin in the first week of life

Bilirubin is produced from the breakdown of red blood cells, and newborns are particularly prone to accumulation because of increased red cell turnover, immature hepatic conjugation enzymes, and enhanced enterohepatic circulation. Unconjugated bilirubin is fat-soluble and can cross the blood-brain barrier, where it is potentially neurotoxic. Conjugation in the liver by uridine diphosphoglucuronosyltransferase 1A1 renders bilirubin water-soluble and safe for excretion in bile and urine.

Several factors influence the rate and severity of physiological jaundice, including gestational age, birth weight, mode of feeding, birth trauma such as cephalohaematoma, and haemolysis from blood group incompatibility. In many Asian populations, the bilirubin rise tends to peak slightly later and reach higher peak levels than in Caucasian infants, although the mechanisms are not fully understood. Genetic variants in UGT1A1, including the Gilbert syndrome-associated TA7 repeat polymorphism, are more common in some East and South-East Asian groups and may contribute to slower bilirubin clearance. A small but important subset of infants also has the c.211G>A variant linked to more pronounced hyperbilirubinaemia, which has been described in Japanese, Korean, and Chinese cohorts.

How phototherapy thresholds are determined

Phototherapy thresholds represent the serum bilirubin level at which the benefits of treatment outweigh the risks and costs of intervention. Modern guidelines use hour-specific nomograms rather than fixed values, because the risk of bilirubin neurotoxicity depends not only on the absolute level but also on the infant's age in hours and the presence of additional risk factors such as haemolysis, sepsis, acidosis, or significant lethargy. The decision matrix typically plots the current serum bilirubin against postnatal age, and treatment is recommended when the value crosses a particular percentile curve.

Evidence for these thresholds comes from observational studies and, where available, randomised trials of prophylactic versus therapeutic phototherapy. The Bhutani nomogram, published in 1999, remains influential and underpins many regional adaptations. Phototherapy itself works by converting bilirubin into water-soluble photoisomers, principally 4Z,15E-bilirubin and structural isomers called lumirubins, which can be excreted in urine and stool without conjugation. The efficacy of treatment depends on the wavelength of light (blue-green spectrum around 460–490 nm is most efficient), irradiance delivered to the skin, the exposed body surface area, and the distance between the infant and the light source.

Comparing major Asian guidelines with Australian practice

Several societies across Asia have published their own phototherapy guidelines, reflecting local epidemiology, average gestational age distributions, and resource considerations. The comparison below summarises key differences for a term, well infant at 72 hours of life without evidence of haemolysis.

Australian thresholds tend to be slightly more permissive than several Asian guidelines, particularly for initiating phototherapy. This reflects historical reliance on the 2004 American Academy of Pediatrics guidelines, which were adopted widely in Australian tertiary centres, alongside local audits suggesting low rates of kernicterus in treated cohorts. A clinician in Parramatta or Footscray assessing an infant of Vietnamese, Filipino, or Sri Lankan heritage may therefore find that the bilirubin level sits just below the Australian threshold yet exceeds the guideline threshold from the family's country of origin. Clear documentation and shared decision-making with the family are essential when thresholds differ, and the rationale for either treating or observing should be explained in plain language with interpreter support if required.

Population-specific considerations for Asian newborns

Beyond the numerical thresholds, several clinical features warrant particular attention in Asian infants. Glucose-6-phosphate dehydrogenase deficiency is common across many Asian populations, with prevalence estimates of 4–6% in parts of southern China, Malaysia, and the Philippines, and higher rates reported in some Burmese, Bangladeshi, and Sri Lankan communities. G6PD deficiency can precipitate haemolysis and rapid bilirubin rises, sometimes after exposure to naphthalene in mothballs, certain antibiotics including sulfonamides and nitrofurantoin, fava beans, or traditional herbal remedies. Asking about family history and, where appropriate, ordering G6PD screening can shift the threshold at which phototherapy is initiated and may also influence decisions about discharge advice.

Breastfeeding jaundice and breast milk jaundice also behave somewhat differently in some Asian populations, partly because exclusive breastfeeding rates in the early postpartum period are high in countries such as Japan, South Korea, and Vietnam. Dehydration and poor intake may contribute more to the bilirubin rise than in predominantly formula-fed cohorts, so skilled lactation support is a critical adjunct to phototherapy. In Australian hospitals with high migrant populations, such as the Royal Women's Hospital in Parkville, Westmead Hospital in western Sydney, or the Women's and Children's Hospital in Adelaide, interpreters and culturally appropriate feeding counselling form part of routine care. Skin colour assessment adds yet another layer of complexity: visual estimation of jaundice using Kramer's rule is less reliable in deeply pigmented skin, and transcutaneous bilirubinometers have variable accuracy across different skin tones. Capillary serum bilirubin remains the gold standard when there is any doubt, and a venous sample is warranted if the transcutaneous reading approaches the treatment zone.

Practical implications for Australian clinicians

For paediatricians, neonatologists, and midwives working across Australia, a sensible approach combines the local guideline with an awareness of population-specific risk factors. When assessing a baby of Asian heritage whose family has recently arrived, consider the following steps: confirm G6PD status if not already done, examine the mother and infant together for signs of breastfeeding difficulty, and use a serum bilirubin rather than relying on visual or transcutaneous assessment if the infant appears deeply jaundiced or the readings are borderline. Documentation should record the guideline used, the hour-specific risk zone on the nomogram, and any factors that pushed the clinician toward earlier treatment.

Parents appreciate a clear explanation, and translating the concept of a "safe bilirubin level" into community languages such as Mandarin, Vietnamese, Hindi, or Tagalog builds trust and improves adherence with follow-up appointments. Professional development in this area is well supported by perinatal societies, and the FAOPS archive offers access to presentations on related neonatal topics such as cystic fibrosis screening, with detailed notes available through neonatal cystic fibrosis screening for clinicians interested in parallel screening programmes. Reflecting on how jaundice management sits alongside other newborn screening priorities helps teams deliver comprehensive early-life care.

If you manage newborns in any capacity, take a few minutes to revisit your local phototherapy protocol and compare it with the Asian regional guidance summarised above. A short audit of recent jaundice admissions in your unit may reveal whether threshold selection is consistent with the population you serve, and whether language-appropriate discharge advice is reaching the families who need it most. Sharing these reflections with colleagues at morbidity and mortality meetings, or within networks such as the Australian and New Zealand Neonatal Network, strengthens collective practice and helps ensure that every baby, regardless of heritage, receives timely and equitable care.