• Alloimmune thrombocytopenia;
  • HPA-1a;
  • intracranial haemorrhage;
  • noninvasive treatment;
  • fetal blood sampling;
  • intravenous immunoglobulins

Objective  To describe the outcome of pregnancies with fetal and neonatal alloimmune thrombocytopenia (FNAIT) in relation to the invasiveness of the management protocol.

Design  Retrospective analysis of prospectively collected data from a national cohort.

Setting  Leiden University Medical Centre, the national centre for management of severe red cell and platelet alloimmunisation in pregnancy.

Population  Ninety-eight pregnancies in 85 women with FNAIT having a previous child with thrombocytopenia with (n= 16) or without (n= 82) an intracranial haemorrhage (ICH).

Methods  Our management protocol evolved over time from (1) serial fetal blood samplings (FBS) and platelet transfusion (n= 13) via (2) combined FBS with maternal intravenous immunoglobulins (n= 33) to (3) completely noninvasive treatment with immunoglobulins only (n= 52 pregnancies, resulting in 53 neonates). Perinatal outcome was assessed according to the three types of management.

Main outcome measures  Occurrence of ICH, perinatal survival, gestational age at birth and complications of FBS.

Results  All but one of 98 pregnancies ended in a live birth; none of the neonates had an ICH. The median gestational age at birth was 37 weeks (range 32–40). In groups 1 and 2, three emergency caesarean sections were performed after complicated FBS, resulting in two healthy babies and one neonatal death.

Conclusion  Noninvasive antenatal management of pregnancies complicated by FNAIT appears to be both effective and safe.