Red Blood Cell Alloimmunization in Pregnancy: A Review of the Pathophysiology, Prevalence, and Risk Factors

Abstract

This review paper provides an overview of the risk factors and laboratory testing for red blood cell (RBC) alloimmunization in pregnancy. RBC alloimmunization is a significant medical issue that can cause haemolytic disease of the fetus and newborn (HDFN), leading to neonatal morbidity and mortality. Current HDFN prophylaxis targets only Rhesus D (RhD) alloimmunization, with no effective measures to prevent alloimmunization to other RBC antigen groups. Several factors can increase the risk of developing RBC alloimmunization during pregnancy, including fetomaternal haemorrhage, RBC and maternal genetic status, and previous transfusions. Identifying these risk factors is essential to execute the appropriate management strategies to minimize the risk of HDFN. The review also discusses the laboratory methods and overview of pregnancy management. The paper highlights the importance of identifying and managing the risk factors for RBC alloimmunization in pregnancy to minimize the risk of HDFN and improve neonatal outcomes.

Keywords: alloimmunization; alloimmunization factors; hdfn; laboratory methods; pregnant; red blood cell.

Figure 1. Prevalence of antibodies among alloimmunized pregnant women from 1995 to 2022.

Anti-D showed the highest antibody that causes alloimmunization among alloimmune patients compared to another antibody due to inappropriate application of RhIg prophylaxis.

Figure 2. The flowchart provides a simplified overview of screening and detection of alloimmunization in pregnancy starting from the first prenatal visit until delivery.

ABO and RhD typing will be screened, followed by antibody screening. If the mother presents with an antibody, the type and significance of the antibody will be identified and will be continuously monitored until delivery.

Figure 3. Factors that influence RBC alloimmunization in pregnant women.

The figure illustrates the factors that influence RBC alloimmunization in pregnant women, a condition where an individual develops antibodies against foreign RBC antigens. This can occur following exposure to antigens through blood transfusions or pregnancy and other complex processes influenced by multiple factors on fetomaternal haemorrhage, RBC antigen, genetic and immunomodulatory.