Thrombocytopenia in Pregnancy: Fetal and Neonatal Alloimmune Thrombocytopenia

Abstract

Fetal/neonatal alloimmune thrombocytopenia (FNAIT) results from the formation by the mother of antibodies that are directed against a fetal platelet alloantigen inherited from its father. The maternal alloantibodies cross the placenta and destroy the baby’s platelets, and the resulting fetal thrombocytopenia may cause bleeding, particularly into the brain, before or shortly after birth. Approximately 10–20 % of affected fetuses have intracranial hemorrhages, one quarter to one half of which occur in utero. There are considerable controversies regarding the optimal management of FNAIT-affected pregnancies. There is no clear approach to the antenatal management of first affected pregnancies, and several questions remain around the approaches to the management of second and subsequent affected pregnancies. Currently, antenatal management of FNAIT consists of weekly maternal intravenous immunoglobulin (IVIg) infusions, with or without oral steroid therapy – the optimal steroid dosages and protocols remain to be defined. Some centers continue to offer serial intrauterine platelet transfusions as first-line therapy, but the multiple cordocenteses required to administer the platelets carry substantial risk of fetal demise. Potential techniques for antenatal screening of first pregnancies are being developed. Postnatal screening does not prevent neonatal morbidity and mortality.