SPONTANEOUS RISE OF FETAL PLATELET COUNTS DESPITE INCREASING ANTI-HPA-5B ANTIBODIES

Background and objectives: Maternal anti-HPA alloantibodies are a rare cause of severe fetal thrombocytopenia. So far there have been no rep orts on the dynamics of maternal anti-HPA-5 during gestation and its e ffect on the fetus. Materials and methods: We monitored maternal anti- HPA-5b antibody titers and fetal platelet counts during gestation in a woman with known anti-HPA-5b alloimmunization. The patient was a 32-y ear-old woman in her third pregnancy. The 1st pregnancy and delivery o f a healthy child had been uneventful. At delivery, anti-HPA-5b was de tectable in the maternal serum. A 2nd pregnancy ended in early miscarr iage. Results: A steady rise in the alloantibody titer was recorded th roughout the 3rd pregnancy. Therefore, cordocentesis was performed at 28 weeks of gestation (platelet count 76x10(9)/l). Serial platelet tra nsfusions were administered to the fetus at 28, 32, and 37 weeks of ge station. The platelet counts rose spontaneously thereafter and were 22 0x10(9)/l at delivery, despite an increase in the anti-HPA-5b antibody titer. The child developed normally during the first year of life. Co nclusions: This case illustrates the spontaneous recovery of fetal pla telet counts in late pregnancy despite a rise in maternal alloantibody titer.