Neonatal alloimmune thrombocytopenia due to anti‐P1^A1 (anti‐hpa‐1a): Importance of paternal and fetal platelet typing for assessment of fetal risk

Neonatal alloimmune thrombocytopenia (NAIT), which usually involves sensitization to P1^A1 (HPA‐1a), may have devastating complications for the fetus. These may be prevented by antenatal treatment of severe cases with either maternally administered high‐dose gamma‐globulin and/or repeated intrauterine platelet transfusions. Determination of the paternal platelet phenotype is useful for counselling parents who have had one or more affected pregnancies. This report of an unaffected pregnancy in a woman with a history of previous pregnancies complicated by NAIT illustrates the role of paternal and fetal platelet phenotyping in managing existing pregnancies at risk of NAIT.