Main findings
In this unselected national cohort of 157 RhD-positive children of 62 women with RhD antibodies, HDFN severity in the first pregnancy with anti-RhD antibodies with a RhD-positive child and subsequent pregnancies at risk was evaluated. The severity of HDFN increased significantly in 56% of women. Women who developed RhD antibodies in the first pregnancy at risk for immunization seemed more prone for severe disease in the subsequent pregnancy.