breast milk jaundice info from emedicine.com

CLARIFICATION: In my previous post I indicated that breast milk had bilirubin. This was incorrect. There is "something" in breast milk that causes an increase in bilirubin, but it is not directly in the milk. Thanks to my friend C who found this article that explains more.

Background: 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.

Please see Jaundice, Neonatal for an in-depth review
of the pathophysiology of hyperbilirubinemia.

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.