Occurrence of anti-D alloantibodies among pregnant women in Kasese District, Western Uganda.

OBJECTIVES: This study was undertaken to determine the distribution of ABO/RhD (rhesus D antigen) blood phenotypes, prevalence of anti-D alloantibodies, and the risk factors for alloimmunization among pregnant women in Kasese District, Western Uganda.

MATERIALS AND METHODS: Ethylenediamine tetraacetic acid-containing plasma samples and serum samples were taken from pregnant women attending the antenatal clinic. The blood groups were identified using the microplate grouping method, while the presence of anti-D alloantibodies was detected by the indirect antiglobulin test (IAT). Data were also collected from the pregnant women on the risk factors associated with anti-D alloantibody formation.

RESULTS: Among the 726 participants, the blood group distribution was as follows: O: 356 (49.%); A: 190 (26.%); B: 152 (21%); and AB: 28 (4%). A total of 28 (3.86%) pregnant women were RhD negative. Anti-D alloantibodies were detected in 88 (12.1%) of the participants; and of these, 13 (14.8%) were RhD negative. Statistically significant risk factors for anti-D alloimmunization included miscarriage, stillbirth, and postpartum hemorrhage.

CONCLUSION: Blood group O was the most common among the pregnant women in this study and the prevalence of Rh negativity was 3.8%. The frequency of anti-D alloimmunization among pregnant women in Kasese District was 12.12%, with 85.5% of these being RhD positive. Risk factors such as a history of stillbirths, miscarriages, and incidence of postpartum hemorrhage were significantly associated with anti-D alloimmunization. There is a need to routinely carry out antenatal blood grouping and IAT screening on pregnant women in Uganda to detect anti-D alloimmunization. Given the high prevalence of anti-D alloantibody formation among RhD-positive women, we recommend additional research studies on the role of autoimmunity among antigen-positive women, as well as the occurrence of RhD variants plus their implications on hemolytic disease of the fetus and newborn, in Uganda.