High‐dose intravenous immunoglobulin in the prenatal management of neonatal alloimmune thrombocytopenia

Neonatal alloimmune thrombocytopenia (NAIT) due to maternal immunization to fetal platelet antigens has previously been estimated to affect 1 in 5000 live births (Pearson et al. 1964). Recently the risk has been assessed at 1 in 1000–2000, mainly due to PLA1 incompatibility (Mueller-Eckhardt et al. 1989). The perinatal mortality rate, mainly due to intracranial haemorrhage (ICH) is about 10–15%. The risk of haemorrhage is probably greatest at the time of delivery but ICH may also occur in utero (Zalneraitis et al. 1979; Lam & Shulman 1985; Reznikoff-Etievant 1988). Early atraumatic delivery has been recommended, and postnatal thrombocytopenia has been treated with steroids, exchange transfusion and transfusion of PLA1 negative platelets, which may be washed maternal platelets. Antenatal treatment has involved paraumbilical fetal blood sampling (PUBS) with in-utero platelet transfusions (Kaplan et al. 1988, Nicolini et al. 1988). Although high-dose intravenous immunoglobulin (i.v.Ig) has been used successfully to treat NAIT in the postnatal period (Suarez & Anderson 1987), its antenatal application has only recently been described for this condition, with variable results (Bussel et al. 1988; Kaplan et al. 1988; Mir et al. 1988). We now report our experience with this treatment.