Breast Milk Jaundice

Breast milk jaundice is prolonged unconjugated hyperbilirubinaemia in an otherwise healthy, thriving breastfed infant, with onset after the first week of life and persistence beyond 2 weeks. It is a benign condition and a diagnosis of exclusion.

It is common in breastfed term infants. Bilirubin usually peaks in the second to third week and resolves by 12 weeks.

Bilirubin is under 250 micromol/L in most infants. Exclusion of cholestasis and treatable causes of prolonged jaundice is needed in every infant with jaundice over 14 days.

Pathophysiology.

Several features of breast milk are suggested to reduce bilirubin clearance: breast milk beta glucuronidase deconjugating bilirubin in the gut and promoting reabsorption (enterohepatic circulation), and substances that inhibit hepatic conjugation. Genetic variants of UDP glucuronosyltransferase 1A1 (the variant underlying Gilbert syndrome) add to risk.

The mechanism is not fully defined. The condition differs from early breastfeeding jaundice, which results from low milk intake and starts in the first days.

• Persistent yellow skin and sclerae in a well infant who feeds well, gains weight appropriately and has normal pigmented stools and yellow urine.
• Normal examination with no hepatosplenomegaly.

Red flags.

• Pale or acholic stools, dark urine or conjugated bilirubin over 25 micromol/L.
• Poor feeding, faltering growth, lethargy, hepatosplenomegaly or dysmorphic features.
• Jaundice beyond 14 days in term infants or beyond 21 days in preterm infants without assessment.

• Total and conjugated bilirubin in every infant with jaundice beyond 14 days (21 days if preterm). Conjugated bilirubin over 17 micromol/L, or over 20% of total bilirubin, is cholestasis and needs urgent assessment.
• Full blood count, reticulocytes, direct antiglobulin test and G6PD enzyme assay when clinically indicated.
• Thyroid function (including that of newborn screening), urine culture and urinary reducing substances.
• Stool colour and weight gain assessment.

Differential diagnosis. Biliary atresia and other cholestasis, hypothyroidism, haemolysis, G6PD deficiency, urinary tract infection, Gilbert syndrome, Crigler-Najjar syndrome, galactosaemia and pyloric stenosis.

• Continue breastfeeding. Interrupting breastfeeding is not usually needed and is not advised unless bilirubin is near the treatment threshold.
• Phototherapy only if bilirubin reaches the gestation specific and age specific treatment threshold.
• Review weight and feeding. If the baby is thriving and conjugated bilirubin is normal, no further treatment is needed.
• Repeat bilirubin in 24 to 48 hours if over 250 micromol/L, or sooner in an unwell infant.

Monitoring. Weight, stool colour and clinical review until jaundice clears. Repeat total and conjugated bilirubin if the jaundice persists beyond 4 to 6 weeks.

Referral and escalation. Same day referral for conjugated hyperbilirubinaemia, pale stools or an unwell infant. Refer for further tests if unconjugated jaundice persists beyond 3 months of age.