Alloimmunization to Rh Antigen (D, C, E, C, E) Among Pregnant Women Attending Antenatal Care in South Western Uganda

Abstract

Introduction

Maternal red cell alloimmunization to Rh antigen in pregnant women occurs when the immune system is sensitized by foreign red blood cell surface antigens, in this case fetal red blood cells, inducing an immune response. Various antigens of blood group systems may cause alloimmunization, especially the Rh, Kel, Fy, JK, and MNS systems. This study aimed to determine alloimmunization to the different frequencies of Rh antigen among pregnant women in South Western Uganda.

Methods

A total of 1369 pregnant women consented and were recruited into a cross-sectional study during their regular antenatal visits during the period August 2020 to July 2021. Samples (4 mL) of anticoagulated and coagulated blood were obtained, and Rh blood grouping including Rh antigen and the indirect antiglobulin test (IAT) was carried out using the agglutination technology of the LISS ID-Card technique in the Ortho Biovue ID-Micro Typing System.

Results

Out of 1369 participants recruited to the study, 78 (5.7%) were D⁻, 1291 were D⁺, and 134 (9.8%) had alloantibodies. Among those with alloantibodies, 115 (85.8%) were D⁺ and 19 (14.2%) D⁻. The percentage alloimmunization according to the Rh antigens was highest in e (9.72%), c (2.48%), C (2.34%) and E (0.94%) antigens. With the ABO system, alloimmunization was highest in blood group B (10.7%), followed by A (10.6%), O (9.2%) and then AB (7.1%). Alloimmunization was more prevalent in D⁻ (24%) than in D⁺ participants (8.9%). Rhesus antigen e was the most prevalent antigen (99.8%), followed by c. The alloimmunization rate of 9.8% among these participants is high, and appears in both D⁺ and D⁻ women. The other Rhesus antigens are seen to cause alloimmunization, with antigen e causing the highest prevalence. In conclusion, there is a need to identify antibodies and study the outcome for clinical significance, especially in D⁺ women, to facilitate proper pregnancy management.

Keywords:

• Rh alloimmunization
• Rh antigens
• hemolytic disease of the fetus and newborn
• pregnant women
• Western Uganda

Ethical Approval

All the participants were taken through the consent procedure and gave their written informed consent to join the study, and parental written informed consent (assent) was obtained for participants under the age of 18 years. The participant protection procedures were followed in conformity with the Declaration of Helsinki. Ethical clearance was sought and obtained from the ethical review board of the School of Medicine as part of a large study at the College of Health Science, Makerere University (REC Ref No 2019-114), and was registered under number HS508ES by the Uganda National Council for Science and Technology.

Disclosure

All authors declare no competing conflicts of interest relevant to the work presented in this article.

Additional information

Funding

This study was partly funded by the Swedish International Development Cooperation Agency (Sida) and Makerere University under Sida contribution No 51180060.