Maternal IgG anti-A and anti-B titres predict outcome in ABO-incompatibility in the neonate.

Aim: To evaluate predictors for risk of severe hyperbilirubinaemia and kernicterus in ABO-incompatible neonates with emphasize on maternal IgG anti-A/-B titres.

Methods: Blood group O women in labour at Oslo University Hospital, Ullevål, were included in the years 2004-2006. Offspring with blood group A or B had direct antiglobulin test performed and IgG anti-A/-B levels measured in maternal plasma. Blood group A or B infants developing severe hyperbilirubinaemia, received in addition to phototherapy, immunoglobulin treatment and/or exchange transfusion (EXT).

Results: Of 253 neonates, 61.3% had blood group O, 29.6% blood group A and 9.1% blood group B. Twenty neonates with blood group A or B received at least one immunoglobulin treatment. In multivariate analysis, maternal antibody-titres were the only significant predictors for immunoglobulin treatment (p < 0.0001), EXTs (p < 0.05) and duration of phototherapy (p < 0.0001). The need for invasive treatment increased sharply for antibody titres > or =512. Receiver operating characteristic analyses demonstrated that titres > or =512 had a sensitivity of 90% and a specificity of 72% for predicting immunoglobulin treatment and thus severe hyperbilirubinaemia.

Conclusion: Maternal IgG anti-A/-B titres contribute to the prediction of risk of severe hyperbilirubinaemia in ABO-incompatible neonates, in addition to blood-grouping and direct antiglobulin-testing, especially following early discharge after delivery.