RESUMO
During pregnancy, irregular blood group antibodies originating either from earlier pregnancies or from blood transfusions may severely affect child health. In this report, a case of maternal alloimmunization to Kell antigen is described.The mother had a history of partial mole and four repeated intrauterine fetal death due to hydrops fetalis.Screening of irregular blood group antibodies revealed that she has anti-Kell with the titer of 1:4096. Also in genetic analysis, a C677T homozygous mutation of MTHFR gene was found, which could potentially enhance destructive effects of anti-Kell antibody. The described case emphasizes the importance of being informed about the presence of irregular blood group antibodies during pregnancy which may cause recurrent hydrops