Contemporary management of neonatal alloimmune thrombocytopenia: good outcomes in the intravenous immunoglobulin era: results from the Australian neonatal alloimmune thrombocytopenia registry.

Objective: To describe the natural history, antenatal and postnatal therapy, and clinical outcomes of Australian patients with fetomaternal/neonatal alloimmune thrombocytopenia (NAIT) recorded in the Australian NAIT registry.

Methods: Analysis of registry data of Australian mothers treated antenatally for NAIT and any fetus/newborn with thrombocytopenia (TCP) and maternal human platelet antigen (HPA) antibodies.

Results: Ninety four potential cases (91 pregnancies; three twin pregnancies) were registered between December 2004 and September 2015 with 76 confirmed or treated as NAIT. NAIT was frequently unanticipated (44 cases, 58%), whilst 32 cases (42%) were anticipated due to personal or family history. In 70/76 cases, the diagnosis of NAIT was made based on HPA antibody results; anti-HPA-1a was most commonly detected (58/70, 82%), followed by anti-HPA-5b (5/70, 7%). Intracranial haemorrhage (ICH) was detected in seven cases (9%). Maternal antenatal therapy resulted in improved clinical outcomes. For antenatally treated cases, whilst 10/29 (34%) neonates had severe TCP, only one ICH was detected.

Conclusions: This study provides data on contemporary "real world" management of Australian mothers and babies with NAIT. Antenatal IVIG therapy was associated with better neonatal outcomes. Maternal side-effects and treatment costs were substantial.