[Epidemiology of anti-D allo-immunization during pregnancy].

The number of women exposed to a risk of anti-D allo-immunization who require care depends on the number of pregnancies, the distribution of blood groups in the Rhesus D system, and the number of allo-immunization risk situations as well as the chosen prevention protocol. In 2004, there were 790,000 pregnancies in metropolitan France. The total number of conceptions (adding abortions, voluntary interruptions, ectopic pregnancies and in utero fetal deaths) would be to the order of 1,100,000 to 1,200,000. Since 15% of the French population is RhD-negative, 15% of pregnant women or women who have delivered are RhD-negative, which would correspond to 160,000 to 180,000 women exposed to a risk of anti-D allo-immunization. Two strategies could be evaluated: prevention targeting risk factors and systematic prevention from 28 weeks gestation. Both strategies involve treatment with anti-D anti-globulins to RhD-negative women with an RhD-positive newborn. Targeted prevention would involve 160,000 to 190,000 doses for 130,000 to 150,000 women. The systematic approach would consist in 300,000 to 340,000 doses for 250,000 to 280,000 women. This number could be lowered by reserving treatment for women with a RhD-positive partner (210,000 to 230,000 doses for 260,000 to 290,000 women), but this would require a precise contract between the physician and the woman. Another way to reduce the number of doses would be to determine the Rh group of the fetus either by ovular samples or by genotyping on maternal blood. This would give about 200,000 to 220,000 doses for 240,000 to 270,000 women. In light of the literature, the systematic protocol would probably reduce the number of immunized women, the current estimation being 700 women still immunized in France and the goal being a reduction to a residual 200. The number of infants at risk of in utero maternal allo-immunization (fetal death, anasark, anemia) or after birth (jaundice, severe anemia) is not known in France and could be the cause of a few deaths with involvement of about a hundred children. In light of experience in other countries, the systematic protocol would enable avoiding a certain number of these deaths.