Table 2.

Characteristics of HDN and FNAIT; strategies for prevention and treatment

	HDFN/HDN	FNAIT
Pathogenesis	Alloantibodies to erythrocyte antigens	Alloantibodies to platelet antigens
Clinical symptoms	Hemolytic disease Most severe: hydrops fetalis	Petechiae, hematomas, melena, hemoptysis, retinal bleeding or hematuria Most severe: ICH in fetus or newborn
Immunization	>95 % cases during delivery; HDN risk in the next pregnancy	75 % of cases during delivery; 25 % of cases during pregnancy
Most frequent and most severe: others	Anti-D; risk in RhD negative women (15 % in Caucasian population) Anti-Rhc; E; K; others	Anti-HPA-1a; risk in HPA-1a negative women (2 % in Caucasian population) Anti-HPA-5a; other HPAs
Antigen characteristics	Rh proteins only on erythrocytes	HPA-1a present on integrin β3 on platelets and vascular endothelial cells
HLA restriction	Unknown	HLA DRB3*01:01
Frequency	1/1000–2000 (in the era of immunoprophylaxis)	1/1000–2000
Screening methods	RhD phenotyping in all pregnant women; anti-RhD examination 3× during pregnancy plus antibodies to other RBC antigens tested 2× during pregnancya	Not performed
Doppler USG	Effective in detecting fetal anemia; therapeutic intervention can prevent hydrops fetalis	ICH can be detected but therapeutic intervention which minimize its effect are limited
Treatment	Effective; standardized	Effective; individualized
Immunoprophylaxis	Available for anti-D; not available for others	Under development for HPA-1a

HDFN hemolytic disease of the fetus and newborn

^aTotal number of tests in Poland 400,000 pregnancies × 5 = 2,000,000