Around 60% of newborns develop jaundice. Most cases are normal and self-limiting — here's how to tell when it needs treatment.
Around 60% of full-term newborns and 80% of premature babies develop jaundice in the first weeks of life.1 The yellow tint to the skin and whites of the eyes is caused by a buildup of bilirubin — a yellow pigment produced when red blood cells break down. Newborns have a high turnover of red blood cells, and their livers are still maturing; the processing lag is what causes the colour.
Most cases are entirely normal and resolve without treatment. Knowing the types, how jaundice spreads, and specifically which signs require urgent action lets you monitor confidently rather than anxiously.
Why newborns get jaundice
When old red blood cells are broken down, bilirubin is released. An adult liver processes bilirubin efficiently; a newborn's liver takes time to reach that capacity. This lag is the cause of physiological jaundice — the most common type.
Bilirubin levels rise after birth, typically peaking between days 3 and 5 in term babies, then falling as the liver matures. In most babies the process completes within two weeks, though breastfed babies can have mild jaundice persisting up to three weeks.1
The four types
Physiological jaundice is the default variant: normal bilirubin processing lag, appears on days 2–4, resolves within 2 weeks in formula-fed babies and up to 3 weeks in breastfed babies. No treatment is usually needed.
Breastfeeding jaundice occurs in the first week when a baby is not getting enough milk. Poor intake means less stool, and bilirubin that should be excreted returns to circulation instead. The fix is improving feeding — more frequent feeds, checking latch, and supplementing if necessary under midwife guidance. This is distinct from breast-milk jaundice.
Breast-milk jaundice is a prolonged form that appears after the first week and can persist for up to 12 weeks.1 Substances in some mothers' milk are thought to slow bilirubin excretion. Levels stay mildly elevated but typically don't reach concerning ranges. Continuing to breastfeed is recommended.
Pathological jaundice starts within the first 24 hours of life, or causes bilirubin to rise unusually fast. Causes include blood group incompatibility (Rh or ABO), G6PD enzyme deficiency, infection, and rare liver conditions. This always requires urgent medical evaluation.2
How jaundice spreads: cephalocaudal progression
Jaundice follows a predictable direction — face first, then the chest and abdomen, then the arms and legs, and finally the palms and soles.1 This head-to-toe spread is a rough indicator of severity:
- Face only: mild — monitor, report to midwife at next visit
- Chest and abdomen: bilirubin probably rising — ask for a formal measurement
- Palms and soles: bilirubin level may be high — contact your midwife or GP today
A bilirubin level is measured by either a skin test (transcutaneous bilirubinometer) or a blood test (serum bilirubin). Both the NHS and AAP use the bilirubin level plotted against the baby's age in hours to determine whether treatment is indicated.2
How to check at home: In good natural light, press a finger gently onto your baby's skin and release. If the skin looks yellow when the colour returns, that's jaundice. This visual check works on all skin tones when done in bright daylight — but it is not accurate enough to replace a measured bilirubin level. Always report visible jaundice to your midwife rather than monitoring at home alone.
What phototherapy looks like
When bilirubin reaches a threshold, phototherapy is recommended. Special blue-spectrum light breaks bilirubin down into a water-soluble form that can be excreted without needing full liver processing. It is not UV light and does not damage skin.
Phototherapy may be given in hospital using overhead lamps or a bili blanket — a fibre-optic blanket wrapped around the baby. It is usually effective within 24–48 hours, after which bilirubin is rechecked. Exchange transfusion (replacing a portion of the baby's blood) is rare and only used at very high bilirubin levels that haven't responded to phototherapy.
Feeding frequently during phototherapy helps: every feed produces stool, and stool is the primary route by which bilirubin leaves the body. Breastfeeding does not need to pause during phototherapy.
Red flags
Contact your midwife, GP, or call 111 urgently if:
- Jaundice appears in the first 24 hours of life — this is never physiological and always needs same-day assessment2
- Yellow colour has spread to the palms and soles
- Your baby is unusually sleepy and difficult to rouse for feeds
- Your baby is feeding poorly or refusing feeds
- Urine is dark yellow or brown in the first weeks (it should be colourless to very pale)
- Stools are pale, chalky white, or clay-coloured (they should be yellow, green, or brown)
- Jaundice persists beyond 2 weeks (formula-fed) or 3 weeks (breastfed) without a medical review
Severe untreated jaundice can cause kernicterus — permanent brain damage that is entirely preventable with timely treatment. If you see these signs, do not wait for your next scheduled appointment.
Feeding and monitoring in the first week
Jaundice is one of the reasons community midwife visits in the first week focus on feeding and weight. A baby who is feeding well, gaining weight, and producing plenty of yellow stools is clearing bilirubin effectively. A baby with poor feeding or weight loss needs bilirubin measured.
If you are discharged before day 5, ask your midwife specifically about jaundice checks — especially if you have a breastfed baby, since breastfeeding jaundice (related to low intake) is more likely if feeding is not well established, and the fix is straightforward when caught early.
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Also in this cluster: Fever: when to worry · When to call the doctor
Sources
- NHS. "Newborn jaundice." NHS, 2023. https://www.nhs.uk/conditions/jaundice-newborn/
- American Academy of Pediatrics. "Clinical Practice Guideline Revision: Management of Hyperbilirubinemia in the Newborn Infant 35 or More Weeks of Gestation." Pediatrics 150(3), 2022. https://publications.aap.org/pediatrics/article/150/3/e2022058859/188333/
Footnotes
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NHS. "Newborn jaundice." NHS, 2023. https://www.nhs.uk/conditions/jaundice-newborn/ ↩ ↩2 ↩3 ↩4
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American Academy of Pediatrics. "Clinical Practice Guideline Revision: Management of Hyperbilirubinemia in the Newborn Infant 35 or More Weeks of Gestation." Pediatrics 150(3), 2022. https://publications.aap.org/pediatrics/article/150/3/e2022058859/188333/ ↩ ↩2 ↩3