BREAST MILK JAUNDICE IN THE NEWBORN

Breast Milk Jaundice
Arias first described breast milk jaundice in 1963. Breast milk jaundice is a type of neonatal jaundice associated with breastfeeding. Specifically, it is an elevation of indirect bilirubin in a breastfed newborn that develops following the first 4-7 days of life, persists beyond physiologic jaundice, and has no other identifiable cause. It should be differentiated from breastfeeding jaundice, which occurs before the first 4-7 days of life and is caused by insufficient production or intake of breast milk.

Pathophysiology: The etiology of breast milk jaundice is under investigation, but this type of jaundice is thought to be caused by a substance in the breast milk that inhibits uridine diphosphoglucuronic acid (UDPGA) glucuronyl transferase resulting in a prolonged unconjugated hyperbilirubinemia. Accumulation of unconjugated bilirubin pigment in the skin causes jaundice. Physiologic jaundice results from immaturity of newborn's liver and its inability to produce enough UDPGA glucuronyl transferase, the enzyme required to conjugate bilirubin. Conjugated bilirubin is water-soluble and can be excreted.

Frequency:
• In the US: Jaundice occurs in 50-70% of newborns. Moderate jaundice (bilirubin level >12 mg/dL) develops in 4% of bottle-fed newborns, compared to 14% of breastfed newborns. Severe jaundice (>15 mg/dL) occurs in 0.3% of bottle-fed newborns, compared to 2% of breastfed newborns.
• Internationally: International frequency is not extensively reported but is thought to be similar to that in the United States.

Race: Whether racial differences exist for breast milk jaundice is unclear, although an increased prevalence of physiologic jaundice exists in babies of Chinese, Japanese, Korean, and Native American descent.
Sex: No known sex predilection exists.
Age: Breast milk jaundice manifests within the first 4-7 days of life and can persist for 3-12 weeks.

History:
• Physiologic jaundice usually manifests in the first 2-4 days of life. This can be accentuated by breastfeeding, which in the first few days of life results in lower calorie intake, especially if milk production starts late. This is known as breastfeeding jaundice. Jaundice that manifests before the first 24 hours of life should be considered pathologic until proven otherwise. In this situation, a full diagnostic workup focusing on evaluation of sepsis and hemolysis should be undertaken.

• True breast milk jaundice manifests during the first 4-7 days of life. A second peak in bilirubin level is noted at approximately the 14th day of life.

• In clinical practice, differentiating between physiologic jaundice from breast milk jaundice is important so that the duration of hyperbilirubinemia can be predicted. Identifying the infants who become dehydrated secondary to inadequate breastfeeding is also important. These babies need to be identified early and given breastfeeding support and formula supplementation as necessary. Depending on serum bilirubin concentration, neonates with hyperbilirubinemia may become sleepy and feed poorly.

Physical:
• Clinical jaundice is usually first noticed in the sclera and the face. Then it progresses caudad to reach the abdomen and below. Gentle pressure on the skin helps to reveal the extent of jaundice, especially in darker-skinned babies; however, clinical observation is not an accurate measure of the severity of the hyperbilirubinemia.

• A rough correlation between blood levels and the extent of jaundice (face, approximately 5 mg/dL; mid abdomen, approximately 15 mg/dL; soles, 20 mg/dL) exists. Therefore, clinical decisions should be based on serum levels of bilirubin. Skin should have normal perfusion and turgor and show no petechiae.

• Neurologic examination, including neonatal reflexes, should be normal, although the infant may be sleepy. Muscle tone and reflexes (eg, Moro reflex, grasp, rooting) should be normal.

• Evaluate hydration status by an assessment of the percentage of birth weight that may have been lost, observation of mucous membranes, fontanelle, and skin turgor.