More than 50 red blood cell (RBC) alloantibodies are known to cause hemolytic disease of the fetus and newborn (HDFN). Although Rh immune globulin (RhIG) prophylaxis has significantly reduced the incidence of pregnancies complicated by anti-D, the need to detect and monitor maternal alloantibodies capable of causing HDFN is still a concern. The prevalence and specificity of these alloantibodies were determined. In this retrospective study, the prevalence and specificities of unexpected RBC

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... ntibodies known to cause HDFN in pregnant women at a tertiary-care facility during a 5-year period were compiled and analyzed. Patient selection was carried out by computerized search of patient data based on an obstetric location and the presence or history of RBC antibody between January 1, 2007, and December 31, 2011. The information was organized by ABO and D status of the patient, antibody specificity, and transfusion needs. Of the 8894 obstetric patients identified during the 5-year period, 264 (3.0%) had one or more unexpected RBC antibodies. Of these 264 women, 107 (40.5%), or 1.2 percent overall, had an alloantibody known to cause HDFN, with a total of 15 different alloantibodies identified. The most common alloantibody found was anti-E (n = 33), followed by anti-M (n = 26) and anti-D (n = 20). In pregnancies of D-women, the most common clinically significant antibodies found were anti-D (n = 20), anti-C (n = 11), and anti-E (n = 2). In pregnancies of D+ women, the most common antibodies were anti-E (n = 31), anti-M (n = 25), and anti-K (n = 16). A total of eight pregnancies with alloantibodies required intrauterine transfusions with the specificities of anti-D; anti-D,-C (n = 2); anti-Db ; anti-D,-S; and anti-E,-c. At a large academic tertiary-care center, approximately 1 in 83 obstetric patients had one or more RBC alloantibodies capable of causing HDFN. Anti-E, -M, and -D were the most frequent specificities, respectively. Immunohematology 2013;29:127-130.