Alloimmune Red Blood Cell Antibodies: Prevalence and Pathogenicity in a Canadian Prenatal Population

The goals of this study were to determine the prevalence and relative frequencies of red blood cell antibodies in a Canadian prenatal population, and to evaluate the fetal and neonatal outcomes of affected pregnancies.

We conducted a retrospective review of pregnancies that screened positive for red cell antibodies between 2006 and 2010. The following antibodies were included: anti-D, -C, -c, -E, -e, -Fya, -Fyb, -Jka, and-Jkb. Cases of anti-Kell as the sole antibody were excluded. Fetal and neonatal outcome data were then collected and analyzed.

The population prevalence of a positive antibody screen was 0.36%. Anti-E was the most frequent antibody at 48.5%, followed by anti-c and anti-Jka. Anti-D made up 6.8% of cases, but had significantly higher titres and was responsible for the majority of severely affected fetuses. Sixteen cases in our series experienced severe adverse fetal or neonatal outcomes. All severe outcomes occurred in cases that had a maximum titre of ≥ 8.

Despite the decreasing incidence of anti-D alloimmunization, anti-D remains responsible for the majority of severe cases of hemolytic disease of the fetus and newborn.