Lower-dose intravenous immunoglobulins for the treatment of fetal and neonatal alloimmune thrombocytopenia: a cohort study

BACKGROUND: Intravenous immunoglobulins (IVIGs) are the cornerstone in the treatment of pregnancies at risk for fetal and neonatal alloimmune thrombocytopenia (FNAIT). The most commonly used dose is 1.0 g/kg/week, not based on any dose-finding study. IVIG is an expensive multidonor human blood product with dose-related side effects. Our aim was to describe the amount of severe thrombocytopenia according to two different doses of IVIG. STUDY DESIGN AND METHODS: We performed a cohort study, where two dosage regimes of IVIG were evaluated in the treatment of pregnant women suffering from FNAIT with a previous affected child without intracranial hemorrhage (ICH). Cases, treated with 0.5 or 1.0 g/kg/week, were selected from the international multicenter No IntraCranial Hemorrhage (NOICH) registry. Outcome was neonatal platelet (PLT) count at birth and amount of severe thrombocytopenia. Furthermore the appearance of ICH was analyzed. RESULTS: A total of 109 women were included in the study, 46 in the 0.5 IVIG group and 63 in the 1.0 IVIG group. There was no difference in PLT count at birth (mean, 112 vs. 119; crude difference, 7; confidence interval [CI], -37.4 to 23.7]) and incidence of severe lthrombocytopenia (<30 x 10(9)/L; n = 7/46 vs. n = 7/63; odds ratio, 1.43 [CI, 0.46-4.42]). No ICH occurred. CONCLUSION: In pregnancies with FNAIT with a previous affected child without ICH, treatment with IVIG in a weekly dose of 0.5 or 1.0 g/kg results in comparable neonatal PLT count at birth and degree of thrombocytopenia.