Half of all newborns develop jaundice; a yellowing of the skin and eyes. Most often, jaundice isn't a concern, but severe cases can cause serious complications.

Jaundice itself isn't a disease. In most cases it occurs because your baby's liver isn't mature enough to metabolize a molecule called bilirubin, which normally forms when the body recycles old or damaged red blood cells.

In the first few days of life, more than half of all full-term babies and as many as 80 percent of premature infants who are otherwise healthy develop jaundice, a yellowish discoloration of the skin and eyes. Although some babies are jaundiced at birth, most develop the condition during the second or third day of life. That's why you may not notice it until after your baby is home.

Screening and diagnosis

Your doctor will likely diagnose jaundice on the basis of your baby's appearance. He or she may also take a small sample of your baby's blood to measure the bilirubin level. Your baby may have additional blood tests if the jaundice requires treatment or if you and your baby have different blood types.

Complications

When bilirubin reaches extremely high levels, especially in newborns ill enough to require treatment in a newborn intensive care unit, it can lead to a rare, but very serious, condition called kernicterus. This disorder causes damage to a newborn's brain, and may lead to deafness, severe developmental disabilities and an unusual form of cerebral palsy.

Especially if your baby was born early, be especially watchful for signs and symptoms of severe jaundice, such as:

• Deep yellow or orange skin tones

• Extreme sleepiness so that it's hard to wake your baby

• High-pitched crying

• Poor sucking or nursing

• Weakness or limpness