Jaundice Associated with Breastfeeding



The three major categories of unconjugated hyperbilirubinemia associated with breastfeeding:

  • Physiologic jaundice:
    • Occurs between 1 and 7 days of life
    • Peaks at 3 to 5 days
  • Suboptimal intake jaundice (SIJ):
    • Currently, there is no consensus for the terminology for jaundice associated with suboptimal intake in a breastfed infant or SIJ.
    • The term “breastfeeding jaundice” has been used historically but this is inaccurate because these infants are not jaundiced because they are breastfeeding; they are jaundiced because their intake of breast milk is not adequate. Until a consensus is reached, this chapter uses SIJ.
    • SIJ occurs in the first 1 to 2 weeks.
  • Prolonged jaundice associated with breast milk feeding or prolonged unconjugated hyperbilirubinemia (PUH):
    • Occurs between 1 and 12 weeks in thriving human milk-fed infants
    • “Breast milk jaundice” has been used historically, yet researchers question this terminology.



  • Physiologic jaundice: 40–60% of infants
  • SIJ: 10% of breastfed infants
  • PUH: 0.5–2% of breastfed infants

Risk Factors

  • Jaundice in first 24 hours (pathologic)
  • Elevated total serum bilirubin prior to nursery discharge
  • Blood type incompatibility
  • Glucose-6-phosphate dehydrogenase (G6PD) deficiency
  • Gilbert syndrome
  • Gestational age <36 weeks
  • Previous sibling receiving phototherapy
  • Cephalohematoma or significant bruising
  • Exclusive breastfeeding
  • Eastern Asian race


  • Normal physiology:
    • Bilirubin is a breakdown product of hemoglobin. Unconjugated bilirubin is bound to albumin, transported to the liver, and conjugated by the hepatic enzyme uridine diphosphate glucuronosyl transferase 1A1 (UGT1A1).
    • Conjugated bilirubin is transported into the small intestines via the bile ducts, where it is modified and excreted in stool.
    • If stooling is delayed, bilirubin is deconjugated by intestinal enzymes and returned to the liver via the portal circulation (enterohepatic circulation).
  • Physiologic jaundice: Bilirubin levels are elevated in newborns due to several factors:
    • Increased hematocrit and red blood cell volume
    • Increased red blood cell lysis due to shorter red blood cell lifespan
    • Impaired bilirubin excretion because of an immature hepatic UGT1A1 enzyme and increased enterohepatic circulation
  • SIJ: Lack of effective breastfeeding causes inadequate milk and calorie intake and results in decreased stooling and increased enterohepatic circulation. Infants may also be dehydrated.
  • PUH: unclear etiology and probably multifactorial. No causative agent has yet been found in breast milk. One theory is that breast milk may unmask underlying genetic disorders such as G6PD deficiency and/or Gilbert syndrome.

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