[Rh (D) alloimmunization and pregnancy. Analysis of the causes after prophylaxis introduction].

Purpose: Prenatal and postnatal prophylaxis of the Rh (D) haemolytic disease of the newborn have clearly reduced the number of cases but still there are alloimmunizations.

Patients and methods: All cases detected in our Hospital in the last 24 years have been reviewed and possible causes analyzed.

Results: From a total of 10,332 deliveries in Rh (D) negative women we have detected 114 anti-D in 86 women. In 74 women anti-D was the only antibody and in 12 there were more antibodies. Data were managed in 3-year periods and we see a progressive decrease in the incidence of alloimmunization with a minimum of 0.03 per 1000 pregnancies in the period 89-91 and a posterior progression to an incidence of 0.12 in the last 3-year period 95-97. The causes were: pregnancies before 1970 in 31, incorrect prophylaxis in 12, despite a correct prophylaxis in 6, previous pregnancies without complete information about the prophylaxis in 13, previous transfusion in 6, previous pregnancies or transfusion in 8 and indetermined in 10.

Conclusion: It is desirable to reduce at minimum the number of Rh (D) alloimmunizations by strictly following the prophylaxis protocols.