Platelet Reactivity and Pregnancy Loss

Although many advances in reproductive medicine have been made during the past quarter century, miscarriage remains the most common complication of pregnancy. Recurrent Miscarriage (RM) is traditionally defined as three or more consecutive losses before 20 weeks post menstruation. A causal factor can be identified in less than half of affected couples, leading to the term idiopathic RM in the remainder. The empiric use of the antiplatelet agent aspirin is widespread in this population as there is a longstanding hypothesis that women affected by RM are already in a prothrombotic state before pregnancy begins. However, there are few studies to date that efficiently evaluate platelet function in this cohort.

Platelet reactivity refers to the ex vivo measurement of platelet responses to various agonists, providing an index of platelet functional capacity. To date, the role of platelet reactivity has not been clarified in the RM population. The aim of this research was to determine the thrombotic risk of this cohort of patients by assessing in vivo platelet function. This was made possible by the development of a novel platelet assay by Dr. Aaron Peace and Professor Dermot Kenny of the Cardiovascular Biology Group at the Royal College of Surgeons in Ireland. This assay uses multiple concentrations of different agonists and thus reflects the complexity of agonist-induced platelet aggregation in vivo. The results revealed that patients with a history of unexplained recurrent first trimester pregnancy loss have significantly greater platelet aggregation to submaximal doses of Arachidonic Acid (AA) compared to an appropriate control group. The heightened response to AA in particular is interesting due to controversy surrounding the therapeutic role of aspirin in RM management. The results of this research study lend further support to re-evaluating the benefit of low dose aspirin in a clearly defined cohort.

Proposed further research involves assessment of the platelet aggregatory response in the RM group at different stages of achieved pregnancy. However examination of Platelet function in normal healthy pregnancy needs to be known to allow comparison. This novel assey provided the opportunity to characterize platelet function throughout the three trimesters of normal pregnancy we now have the opportunity to provide comparisons to pregnancies complicated not only by RM but other pathologies such as intra-uterine growth restriction (IUGR) and pre-eclampsia (PET).