Irregular antibodies in pregnancy during the universal anti-RHD prophylaxis era: a survey of Spanish Hospitals

Abstract

Background: Although great advances have been made in the prevention of hemolytic disease of the fetus and newborn, especially for anti-D, irregular antibodies still appear. In order to ascertain the situation in Spain, we conducted a survey among hospitals treating pregnant women.

Materials and methods: We sent a survey to Spanish public hospitals comprising demographical data (ethnicity, number of pregnancies, type of fertilization), characteristics of antibodies (specificity, number, antigenic compatibility), cause of alloimmunization and the clinical consequences (fetal death, icterus, anemia) between 2016 and 2021. We characterized the risk posed by antibodies and their clinical impact according to previously described criteria.

Results: During the study period, 574,140 children were born in the responding hospitals. Antibodies were detected in 1,055 women with 1,112 pregnancies, resulting in a 0.19% alloimmunization prevalence. The most common antibodies were anti-D (No.=393, 28.7%), anti-c (No.=204, 14.9%), anti-E (No.=199, 14.6%), anti-M (No.=129, 9.4%), and anti-Kell (No.=114, 8.3%). Incorrect prophylaxis administration in the current or past pregnancy accounted for 88.6% of anti-D, and 12 (6.5%) arose from an RhD-positive transfusion. When analyzing incompatible pregnancies (No.=424; 38%), 103 (24.3%) presented severe or very severe hemolytic disease, most of which (No.=92, 89%) were produced by high-risk antibodies, while only 11 cases were caused by medium-risk antibodies.

Discussion: The prevalence of irregular antibodies during pregnancy in Spain is lower than previously described for other Western countries. The most important antibodies are anti-D, anti-c and anti-K. More efforts to characterize antibodies should be made in order to reduce their prevalence and clinical impact.