The newborn with jaundice: a case-based approach

The case: a yellow baby on day three

A baby is three days old and the parents notice the skin and the whites of the eyes look yellow, first on the face and then spreading down. The baby is feeding, alert and having wet and dirty nappies. This picture — jaundice appearing after the first day and peaking around days three to five — is very common and usually harmless. It happens because newborns have extra red blood cells that break down after birth, releasing a yellow pigment called bilirubin, and a baby's liver takes a little time to clear it. As feeding establishes and the liver matures, the yellow colour fades over one to two weeks in most babies.

Why newborns turn yellow

Bilirubin is made when the body breaks down old red blood cells. Before birth, the mother's body clears it, but afterwards the baby must do this alone. Newborns start with more red cells than they need and their liver is still getting up to speed, so bilirubin can build up faster than it is removed, tinting the skin and eyes yellow. This ordinary process is called physiological jaundice. It is more noticeable in babies born a little early and in those who are slow to feed, because feeding helps clear bilirubin through the gut. Understanding this explains why most jaundice is expected and why good feeding support is often the main thing a baby needs.

The timing clues that matter

When jaundice appears is one of the most important clues. Jaundice in the first 24 hours of life is never assumed to be normal and always needs urgent assessment, because it can signal a problem such as blood group incompatibility or infection. Jaundice that appears after day one and settles within two weeks is usually the harmless kind. Jaundice that is still there after two weeks (or three weeks in a premature baby) is called prolonged jaundice and needs review, including a check of the baby's stool and urine colour. Pale, chalky stools with dark urine can point to a rare but serious liver problem that must not be missed, so timing genuinely guides the whole assessment.

How doctors measure and treat it

Rather than judging by eye alone, which is unreliable, clinicians measure bilirubin — with a light meter on the skin or a blood test — and plot the level against the baby's age in hours on a chart. This shows whether the level is safe, needs rechecking, or needs treatment. The main treatment is phototherapy: the baby lies under a special blue light that changes bilirubin into a form the body can remove more easily. It is safe and widely used. Very high levels that do not respond may occasionally need a specialised blood exchange in hospital. Good feeding is encouraged throughout, as it helps the baby clear bilirubin naturally.

When jaundice is an emergency

Most jaundiced babies do well, but certain signs need urgent action. Jaundice in the first day of life, a baby who is very yellow or yellow to the legs and feet, a baby who is sleepy and feeding poorly, high-pitched crying, arching of the body, or a floppy or unwell-looking baby all need immediate medical review. Very high bilirubin can, rarely, harm the developing brain, which is why doctors act promptly on these signs. In our illustrative case, the alert, feeding baby with jaundice from day three would simply be monitored and supported — but the same yellow colour with poor feeding or on day one would be treated as urgent. Parental instinct that something is wrong should always be acted on.