A group B premature infant (mother group A(2)), which was transfused 12 ml fresh frozen plasma and subsequently required three exchange transfusions, was found to be suffering from ABO haemolytic disease of the newborn. It was considered that the principal factor responsible for the degree of jaundice experienced by the infant was the swamping of its ‘protective mechanism’ by maternal high-titre IgG anti-B, and that its prematurity and the administration of fresh frozen plasma had only minimal effect.

A rapid and simple method of demonstrating the presence of high titre IgG anti-A or anti-B (anti A/B) is described. The method requires the separation of IgG anti-A/B from IgM anti-A/B using DEAE Sephadex A-50 by a simple spin technique, and the subsequent titration of the IgG fraction to detect the presence of high titre IgG anti-A/B. Since high titre IgG anti-A/B is usually associated with ABO incompatibility the test is a useful guide to the prediction of ABO incompatibility in routine antenatal samples.