Predicting anaemia and transfusion dependency in severe alloimmune haemolytic disease of the fetus and newborn in the first 3 months after birth.

Infants with haemolytic disease of the fetus and newborn (HDFN) often require erythrocyte transfusions in the first 3 months of life. We aimed to evaluate the incidence, timing and potential predictors of transfusion-dependent anaemia. An observational cohort of 298 term and near-term infants with severe HDFN treated with or without intrauterine transfusion (IUT) was evaluated. Transfusions were administered to 88% (169/193) of infants with IUT and 60% (63/105) without IUT. The following potential predictors were associated with less anaemia: K compared to D immunisation [odds ratio (OR) 0·13, 95% confidence interval (CI): 0·03-0·55], higher reticulocyte count at birth [per 10 parts per thousand (‰) higher, OR 0·99, CI: 0·97-1·00] and exchange transfusion (OR 0·11, 95% CI: 0·03-0·50). Without IUT, these variables were: lower reticulocyte count at birth (per 10‰ lower, OR 1·02, 95% CI: 1·00-1·03), lower maximum bilirubin after birth (per 10 μmol/l lower, OR 1·01, 95% CI: 1·01-1·02) and exchange transfusion (OR 0·07, 95% CI: 0·01-0·20). In conclusion, potential predictors for anaemia in infants with severe HDFN varied between infants treated with and without IUT and are useful for selecting subgroups of infants at increased risk of anaemia.