[Frequencies of blood groups, ABO and Rh D incompatibility in post-delivery women and their liveborn].

Objective: This study aimed to assess the frequency of different blood phenotypes and to predict the risk of Rh D alloimmunization and maternal-fetal incompatibility in a Brazilian population living in the West zone of the city of São Paulo-Brazil.
Methods: This descriptive study evaluated 2,372 post-delivery women and their liveborn during one year. Blood types were analyzed by means of tube agglutination tests.
Results: The blood type frequencies were: 50.67 O, 32.17 A, 13.45 B, 3.75 AB, 90.34 Rh D(+) and 9.66 Rh D(-). ABO maternal-fetal incompatibility was detected in 18.4% and Rh D incompatibility in 7%.
Conclusion: The fraction of Rh D(-) population at high risk for Rh D alloimmunization was 82%, emphasizing the importance of Rh D alloimmunization profilaxis.