About 2% of healthy breast fed term babies develop significant jaundice after the 7th day of life. This is believed to be caused by the presence of an enzyme (glucuronidase) in the maternal milk that interferes temporarily with the normal bilirubin elimination pathways of the liver. Breast milk jaundice tends to run in families. It occurs equally often in males and females. The elevation of bilirubin levels in the blood is usually not to a harmful degree (but can very rarely reach levels that are dangerous). In the usual situation, even if the mother continues to nurse, the bilirubin levels will fall to normal gradually over a period of 3 to 10 weeks. However, if mother simply stops nursing for one or at most two days (she can pump and store the milk for later use if she so desires), the jaundice rapidly resolves. Nursing at the breast is resumed as if nothing had happened and proceeds uneventfully and the condition does not reappear. There is no reason to totally stop nursing.
Warning: The CDC has recently reemphasized the danger of assuming that jaundice in nursing newborns is simple breast milk jaundice and failing to check blood levels of bilirubin. Visual estimation of blood bilirubin levels is unreliable and has led to tragic outcomes. While the benefits of nursing are clear, everyone involved - parents and physicians -must understand that careful monitoring of a baby's progress in establishing effective nursing is critical. This means careful attention to the baby's weight gain by frequent weighing on calibrated scales and careful monitoring of bilirubin levels, with actual laboratory determination of the level to confirm clinical estimation whenever there is any uncertainty. Also, it is imperative to remember that true breast milk jaundice is a phenomenon that develops later. In the tragic cases of brain damage detailed in a recent CDC report, jaundice appeared early - sometimes in the first few hours of life, a "dead giveaway" that it was not breast milk jaundice. Early onset jaundice is not breast milk jaundice and has to be investigated and treated appropriately.