Anti-D IgG1 with lower core fucosylation induces more severe haemolysis. No significant correlation was found between anti-D titre and Haemoglobin levels (A). However, the degree of IgG1-anti-D fucosylation in pregnancy correlated significantly with fetal or neonatal haemoglobin levels (B). Statistical analyses were performed using one-tailed Pearson correlation with significance set at P = 0·05. NS: not significant.