How jaundice occurs
Before birth, babies need high levels of red blood cells to get oxygen from their mother's blood. Immediately after birth, they no longer need their fetal haemoglobin, so the red blood cells containing fetal haemoglobin need to be broken down. Bilirubin is a by-product of the breakdown of these extra blood cells, and is removed from the bloodstream by the liver and excreted. The newborn's liver may not be able to process and excrete the bilirubin fast enough, so jaundice often develops.
Very rarely, bilirubin can rise to dangerous levels and cause brain damage, and jaundiced babies are usually monitored so treatment can be initiated before levels become problematic. Warning signs include jaundice that lasts for more than two weeks, very yellow urine and whitish stools.
Pathologic jaundice is usually caused by blood-type incompatibilities, as well as prematurity, infection, liver damage and hypothyroidism.
Treatment
For physiologic jaundice, the skin is exposed to blue light that breaks down the bilirubin. Prolonged jaundice is normally caused by liver disease and tests will be needed to establish the cause. Very rarely, blood transfusions may be necessary.