When babies are born, it’s not uncommon for their skin or eyes to yellow, which is called jaundice. The condition affects an estimated 50 percent of newborns.

“Fetuses have a certain kind of hemoglobin, which is the oxygen-carrying molecule in your red blood cells,” says Dr. Pilar Bradshaw. “Fetal hemoglobin is dumped, as soon as the babies are born, and replaced with the adult-type that stays with us our whole life. All that waste product contains iron, which turns the skin yellow until the baby’s liver and gut is able to get rid of it.”

That waste product, a chemical called bilirubin, is what causes jaundice. It usually appears in the second or third day of a newborn’s life. Prolonged jaundice can be dangerous, causing damage to an infant’s brain, but hospitals and pediatricians are equipped to spot it early with a non-invasive device called a transcutaneous bilirubin meter.

“The device has a sensor that registers the amount of bilirubin in the skin on the baby’s forehead. It tells us which babies we need to keep an eye on or treat for jaundice,” says Dr. Bradshaw.

There are several causes of jaundice:

  • Physiology: This is the most common type of jaundice, and it usually goes away on its own.
  • Prematurity: Babies who are born more than 4 weeks early are at a higher risk of developing jaundice.
  • Extensive bruising: Jaundice is more common in babies who develop extensive bruising, which can occur during a rapid delivery.
  • Blood group incompatibility: The most severe cases of jaundice can occur when the baby’s blood type is different than the mother’s blood type. The mother’s antibodies may enter the baby’s system and break down the blood cells, which releases bilirubin.

Treating jaundice
In mild or moderate cases, jaundice will resolve on its own in one to two weeks, as the baby consumes more fluids. For babies with higher levels of bilirubin, phototherapy is needed.

“It’s a UV light source that will help the baby’s body process bilirubin from something it cannot easily excrete to something that it can,” Dr. Bradshaw says.

For answers to frequently asked questions about jaundice, click here.