Annotations on the hyperbilirubinaemia of ABO incompatible infants.

In ABO incompatible infants, a strong association between Coombs test positivity and hyperbilirubinaemia in the first few days of life has been recorded in all samples studied. A remarkable variability between ethnic groups and between different series of infants from the same group has been also observed. A discriminant analysis carried out on several maternal and neonatal variables in two samples of ABO incompatible infants has shown that the Coombs test is the most important predictor of jaundice. Gestational age and birth weight in white and birth weight in black infants gave also important and independent contributions as discriminating variables. Among ABO incompatible black infants the incidence of hyperbilirubinaemia was higher than among ABO incompatible white infants. Discriminant analysis suggests the genetic and environmental factors which predispose to jaundice the ABO incompatible black infants may act mainly through immunological and developmental mechanisms accounted for by Coombs test, gestational length and birth weight.