Definition of Newborn jaundice:

Newborn jaundice is a condition marked by high levels of bilirubin in the blood. The increased bilirubin cause the infant's skin and whites of the eyes (sclera) to look yellow.

Causes, incidence, and risk factors:

Bilirubin is a yellow pigment that's created in the body during the normal recycling of old red blood cells. The liver processes bilirubin in the blood so that it can be removed from the body in the stool.

Before birth, the placenta -- the organ that nourishes the developing baby -- removes the bilirubin from the infant so that it can be processed by the mother's liver. Immediately after birth, the baby's own liver begins to take over the job, but this can take time. Therefore, bilirubin levels in an infant are normally a little higher after birth.

High levels of bilirubin in the body can cause the skin to look yellow. This is called jaundice. Jaundice is present to some degree in most newborns. Such "physiological jaundice" usually appears between day 2 and 3, peaks between days 2 and 4, and clears by 2 weeks. Physiological jaundice usually causes no problems.

Breast milk jaundice is another common, usually non-harmful form of newborn jaundice. Breast milk may contain a substance that increases reuse of bilirubin in the intestines. Such jaundice appears in some healthy, breastfed babies after day 7 of life, and usually peaks during weeks 2 and 3. It may last at low levels for a month or more.

Breastfeeding jaundice is a type of exaggerated physiological jaundice seen in breastfed babies in the first week, especially in those that are not nursing often enough. It is different than breast milk jaundice in that it occurs later and is caused by the milk itself.

Sometimes jaundice can be a sign of a serious underlying problem. Higher levels of bilirubin can be due to:

• An event or condition that increases the number of red blood cells that needs to be processed
• Anything that interferes with the bodyâ ' s ability to process and remove bilirubin

The following increase the number of red blood cells that need to be processed:

• Abnormal blood cell shapes
  • Congenital spherocytic anemia
  • Elliptocytosis
• Blood type incompatibilities
  • ABO incompatibility (Mother has type O blood, baby does not)
  • Rh incompatibility (Mother is Rh negative, baby is not)
• Cephalohematoma or other birth injury
• Glucose-6-phosphate dehydrogenase deficiency
• High levels of red blood cells (polycythemia)
  • More common in small for gestational age babies
  • More common in some twins
• Infection
• Prematurity
• Pyruvate kinase deficiency
• Transfusions

The following interfere with the body's ability to process and remove bilirubin:

• Alpha-1 antitrypsin deficiency
• Biliary atresia
• Certain medications
• Congenital cytomegalovirus (CMV) infection
• Congenital herpes
• Congenital hypothyroidism
• Congenital rubella
• Congenital syphilis
• Congenital toxoplasmosis
• Crigler-Najjar syndrome
• Cystic fibrosis
• Gaucher's disease
• Gilbert syndrome
• Hypoxia
• Infections (such as sepsis)
• Lucey-Driscol syndrome
• Neonatal hepatitis
• Niemann-Pick disease
• Prematurity

In otherwise healthy babies born at 35 weeks gestation or greater, those most likely to eventually develop signs of newborn jaundice are those who have:

• A brother or sister who needed phototherapy for jaundice
• A high bilirubin level for their age, even if they are not yet jaundiced
• Been exclusively breastfeed, especially if weight is excessive
• Blood group incompatibility or other known red blood cell disease
• Cephalohematoma or significant bruising
• East Asian ancestry
• Jaundice in the first 24 hours of life