There are several types of jaundice. The most common type among premature babies is exaggerated, physiologic jaundice. In this condition, the liver, which helps filter waste products from the blood, cannot rid the body of bilirubin, a substance produced during the normal breakdown of red blood cells. As a result, bilirubin accumulates in the baby's blood and spreads into the tissues. Because bilirubin is a yellowish color, the baby's skin takes on a yellowish tint.

Phototherapy-placing a baby under bright lights-is the standard treatment for jaundice. During treatment, the baby's eyes are covered with eye patches to protect them from glare. The baby is turned from front to back, or lights both overhead and underneath the baby are used, so that all of the skin is exposed to the light. The light helps break down the bilirubin into a substance that the body can excrete more easily. Usually phototherapy is needed for about a week, and after that, the liver is mature enough to excrete bilirubin on its own.

Jaundice is usually not a serious problem. However, if the bilirubin level gets too high, causing bilirubin toxicity, bilirubin can accumulate in the brain and cause brain damage.