Severity of HDFN in the first immunized and the subsequent pregnancy
In this cohort of 157 RhD-positive children out of pregnancies complicated by RhD antibodies, no children died as a result of HDFN. One foetal death occurred due to a cause other than HDFN (severe growth restriction and placental infarction by pathological examination). As the severity of HDFN of this deceased child cannot be categorized nor compared to the subsequent children (4 RhD-positive children since detection of antibodies), it is not reported in outcome tables and figures.
In two twins, both in the first immunized pregnancy and all RhD-positive, all children showed mild disease.
Table 2 demonstrates that the severity of HDFN was significantly higher in the subsequent pregnancies, compared to the first immunized pregnancy (P <.001). HDFN was more severe in the subsequent pregnancy in 34/61 women (56%, maximum of three categories more), equally severe in 19/61 (31%) and less severe in 8 women compared to the first immunized pregnancy (13%, maximum of one HDFN category less). For two patients HDFN severity was missing an thus imputed, the sensitivity analysis without these patients showed a similar result (P <.001). Figure 2A demonstrates the severity of HDFN in subsequent pregnancies in relation to the severity in the first immunized pregnancy. HDFN severity in third and later pregnancies is available in supplemental table S2 and the accompanying text.
Table S3 presents the raw data on indicators of HDFN and treatment details in first immunized pregnancies and in subsequent pregnancy with a RhD-positive child. Most of these disease parameters indicated more severe disease in the second immunized compared to the first immunized pregnancy (upon eyeballing).