Fetal and neonatal alloimmune thrombocytopenia ( <scp>FNAIT</scp> ): Survey of <scp>UK</scp> fetal medicine centres on antenatal management of subsequent affected pregnancies

Summary Fetal and neonatal alloimmune thrombocytopenia (FNAIT) is a rare condition associated with severe fetal thrombocytopenia and intracerebral haemorrhage. Antenatal management of subsequent pregnancies relies on intravenous immunoglobulin (IVIg); yet, practice varies internationally and UK data are limited. We conducted a national survey to characterise the current antenatal management of FNAIT across UK regional fetal medicine centres using an electronic, scenario‐based design. Responses were analysed descriptively, with ≥75% concordance considered strong agreement. Sixteen of 22 regional fetal medicine centres (73%) responded; all respondents were fetal medicine specialists or haematologists. There was strong consensus to treat standard‐ and high‐risk pregnancies associated with anti‐human platelet antigen (HPA)1a or anti‐HPA5b antibodies using weekly IVIg, most commonly at a dose of 1 g/kg/week. Earlier initiation of IVIg was favoured for high‐risk pregnancies, while timing was more variable for standard‐risk cases. Corticosteroids were not routinely used in standard‐risk pregnancies but were considered in high‐risk scenarios. Fetal blood sampling and intrauterine platelet transfusion were generally avoided. Considerable variation was observed in delivery planning and in the management of pregnancies at risk without a prior confirmed diagnosis. This survey demonstrates the areas of both consistency and variation in UK practice, highlighting gaps in the evidence base and priorities for future research and guidelines development.