RESUMEN
The diagnosis of fetomaternal alloimmune thrombocytopenia (FMAT) was made in a newborn with thrombocytopenia and intracranial hemorrhage. The first child of the family was severely affected with neurodevelopmental sequelae secondary to intracranial hemorrhage. According to the maternal HPA phenotype, close to 100% of subsequent pregnancies could be expected to be affected as the homozygous state was observed in both platelet systems. Another infant was born after a poorly followed pregnancy and was affected as was his elder brother. Prednisolone was given during another pregnancy. A thrombocytic newborn without intracranial hemorrhage was delivered by prudent cesarian section. The infant received platelet transfusion (maternal platelets). We present case histories of FMAT, and stress the conditions for prenatal diagnosis and management.