Epidemiology

About 15% of the white population has an RhD-negative blood type.[3] Population data suggest that the incidence of RhD negativity is highest among Basques (36%).[3] Around 6% to 7% of black people and less than 1% of American Indian and Asian people have an RhD-negative blood type.[3][4]​​ Rh alloimmunization due to RhD has declined markedly as immunoprophylaxis has become routine practice.[5][6]​​ Societal factors, such as delayed childbearing and smaller families, also may have contributed to this decline.[5]

The estimated global prevalence of Rh hemolytic disease is 276/100,000 live births; in countries with well-established perinatal-neonatal care, the prevalence is approximately 2.5/100,000 live births.[7] One survey in Canada estimated that 8/100,000 infants are affected by maternal anti-D antibodies.[8]​ In the US, the reported incidence of Rh hemolytic disease ranges from 1.0 to 6.8/1000 live births; the higher rate may reflect improved identification and reporting of sensitized women and increasing prevalence of atypical, non-RhD antibodies for which immunoprophylaxis regimens are unavailable.[9][10]​​​[11]​

The relative frequency has been reported for several of these non-RhD antibodies.[9] In a large prospective series including over 300,000 consecutive patients, about 1% of pregnant women had alloantibodies detected in the first trimester.[12] Of these, the prevalence of alloantibodies other than anti-D was 328/100,000, of which 191/100,000 implied a risk for occurrence of hemolytic disease of the fetus and newborn as the father carried the antigen. The most common non-anti-D antibodies were anti-K and anti-c.[12]

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