Severity of HDFN according to the time of antibody detection
Figure 2B and C illustrate severity of HDFN in subsequent pregnancies in relation to the severity in the first immunized pregnancy for the subgroups with RhD antibodies detected after giving birth to a RhD-positive child (A), or during the first pregnancy at risk for immunization (B). The median HDFN severity was mild in the first immunized pregnancy in both subgroups and did not differ significantly between group A and B (P =.794). In both subgroups, disease severity increased significantly in the subsequent pregnancy as compared to the first pregnancy (more severe in 14/27 (52%) women in group A, equal in 10 (37%) equal and less severe in 3 (11%), P =.007, and 18/25 (72%) more severe, 4 (16%) equal and 3 (12%) less severe in group B, P =.001). The change in HDFN severity in subsequent pregnancies did not differ between these subgroups (both median +1 HDFN categories change, range -1 to +3), P =.053).
In group A, 6/27 (22%) of women experienced severe HDFN in the second pregnancy, as opposed to 12/25 (48%) of women that developed antibodies in the first pregnancy at risk (group B, OR 3.22, 95% CI 1.0-10.8,P =.051).