Neonatal Jaundice: Causes, Levels, and When to Worry

Up to 60% of full-term newborns and 80% of preterm babies develop some degree of jaundice in the first week of life. In most cases, it is harmless and resolves on its own. However, very high bilirubin levels can cause a rare but serious brain injury called kernicterus.

Why Do Newborns Get Jaundice?

Newborns produce more bilirubin than adults because they have more red blood cells and these cells break down faster. Their immature livers are sometimes slow to process bilirubin, causing it to build up and yellow the skin and eyes.

Risk Factors for Severe Jaundice

• Preterm birth (before 37 weeks)
• Bruising or cephalohematoma from birth
• Blood group incompatibility (e.g., ABO or Rh incompatibility)
• G6PD deficiency
• Exclusive breastfeeding with poor intake
• Family history of jaundice requiring phototherapy

Warning Signs to Seek Immediate Care

• Jaundice appearing within the first 24 hours of life
• Rapid spreading of yellow color to the legs and soles
• Baby is very sleepy, difficult to wake, or not feeding well
• High-pitched crying or arching of the body
• Fever or decreased urine output

Treatment Options

Phototherapy—special blue light that breaks down bilirubin in the skin—is the standard treatment for moderate to high levels. In severe cases, an exchange transfusion may be needed. Frequent feeding helps bilirubin pass through the gut.

Use our neonatal jaundice risk calculator to assess phototherapy thresholds based on age and bilirubin level.