Navajo jaundice: A variant of neonatal hyperbilirubinemia associated with breast feeding

A clinical and chemical appraisal of 47 newborn Navajo infants demonstrated a high incidence of unconjugated hyperbilirubinemia during the first week of life. Within this study population two subgroups were identified: (1) breast-fed infants in whom inhibition of bilirubin glucuronyl transferase activity was related to a substance in colostrum and breast milk in the first days of life and (2) a smaller subgroup of bottle-fed infants who had significant jaundice when compared with a control population from New York. The serum bilirubin concentrations of the Navajo bottle-fed infants never achieved those of the breast-fed subgroup. These data suggest that to some extent the neonatal unconjugated hyperbilirubinemia noted in the Navajo Indian is related to breast feeding, with earlier transmission of the presumed inhibitor substance than previously observed in a Caucasian population.