Clinical input of anti-D (anti-RH1) microtitration in the management of D negative (RH:-1) pregnant women. Experience of the French National Reference Center For Perinatal Hemobiology (CNRHP) - 05/08/26

Doi : 10.1016/j.tracli.2026.07.002

Marion Coux ^a, Jenny Beaud ^a, Cecile Toly-Ndour ^a, Vincent Thonier ^a, Stephanie Huguet-Jacquot ^a, Elodie Maenulein ^a, Michel Vaubourdolle ^b, Agnès Mailloux ^a,⁎

^a Fetal and Perinatal Hemobiology Department–National Reference Center for Perinatal Hemobiology (CNRHP), DMU of Medical Biology and Genomics (BioGeMH), Hospital Saint-Antoine, AP–HP, Sorbonne University, 184, rue du Faubourg Saint-Antoine, 75012 Paris, France

^b Department of Biochemistry, Hormonology and Therapeutic Monitoring, Saint-Antoine Hospital, DMU BioGeMH, AP–HP, Sorbonne University, Paris, France

^⁎ Corresponding author.

Sous presse. Épreuves corrigées par l'auteur. Disponible en ligne depuis le Wednesday 05 August 2026

Highlights

•	Anti-D microtitration, key tool for distinguishing passive from immune anti-D.
•	Anti-D microtitration for dose adjustment in cases of fetomaternal hemorrhage.
•	Anti-D microtitration to avoid RhIg injection.
•	Routine use of anti-D microtitration to improve care for D-negative pregnant women.

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Abstract

Background and objectives

The administration of anti-D immunoglobulin (RhIg) has significantly reduced the incidence of anti-D alloimmunization. However, it complicates the interpretation of antibody screening, as it is necessary to distinguish passive anti-D from early alloimmunization. Microtitration is the reference method for making this distinction. The aim of this study was to evaluate the impact of anti-D microtitration on the immuno-hematological and clinical management of RH:-1 (D-) pregnant women in the CNRHP in 2024.

Materials and methods

This retrospective observational study included all anti-D microtitrations performed between January 1st and December 31st, 2024 in the CNRHP. The anti-D microtitration impact was analyzed in three settings: antenatal care, delivery, and fetomaternal hemorrhage (FMH).

Results

A total of 3281 microtitrations were performed. Antenatally, 84.6% of results matched the expected anti-D levels, while 10.5% were higher, leading to 11 diagnoses of alloimmunization. At delivery, 603 microtitrations identified two new alloimmunizations and prevented RhIg injections in 30 patients. In FMH setting 11.3% of the cases required multiple doses, with microtitration being essential for assessing neutralization. This was especially observed in massive FMH.

Conclusion

The CNRHP's experience highlights that anti-D microtitration is an essential tool for distinguishing passive from immune anti-D, enabling early detection of alloimmunization, avoiding unnecessary monitoring and RhIg injections, and optimizing dose adjustment in cases of FMH.

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Keywords : Anti-D, Titration, Fetomaternal hemorrhage, Pregnancy, Immunoprophylaxis