A prospective study on the prevalence of red cell alloimmunization via fetomaternal hemorrhage and its association with bad obstetric history

Background and Objectives: The presence of irregular red cell antibodies in the serum of pregnant women is named maternal alloimmunization. Sensitizing events such as traumatic delivery and miscarriage can cause fetomaternal hemorrhage, increasing the risk of alloimmunization. Our objective was to estimate the prevalence of red cell alloantibodies among multigravidae and to study its association with those cases with bad obstetric history (BOH). Methods: This was a 1-year cross-sectional study done on 900 multigravidae in the Department of Transfusion Medicine, Medical College, Thiruvananthapuram. We excluded patients with a history of blood transfusion. Results: Out of 900 subjects, 49 (5.4%) were alloimmunized. The RhD-positive cases were predominant (77.4%), while 203 (22.6%) were RhD negative. Among the D-positive women, the prevalence of alloimmunization was 1.3%. The most frequent alloantibody identified was anti-D, followed by anti-G (18.4%). The alloantibodies identified among RhD-positive were anti-E, anti-c, anti-C, anti-Fya, anti-M, anti-Jka, and anti-Leb. We identified a total of 58 clinically significant alloantibodies. Thus, Rh blood group alloantibodies constitute 93.1% and the remaining 6.9% by other blood groups. Out of 159 cases with BOH, 17 were alloimmunized, and there was a statistically significant association between them (P = 0.001). Conclusion: Alloantibodies potentially causing hemolytic disease of the fetus and newborn were found in D-negative (19.7%) and D-positive (1.3%) mothers. The clinicians should change the current practice of screening only D-negative pregnant women, and antibody screening should be offered to all females or at least those with BOH. We may thus ensure early detection and periodic monitoring of all alloimmunized women.