The issue of whether or not antibody quantity during pregnancy is related to severity of neonatal alloimmune thrombocytopenia remains unresolved. In this article we cite studies in support of both sides of the argument and highlight some of the reasons that may lie behind the observed differences amongst those studies. It may well be that some of the reasons for the discrepant results could be due to the type of study carried out (eg retrospective versus prospective), the sample size, the timing of antibody sampling, and possibly the type or protocol of assay used. Another major reason is the absence, until recently, of an international anti-HPA-1a standard.