Secondary objectives: evaluation of the effect of TXA on women with PPH, through monitoring the platelet function (multiplate analyser), plasmatic levels of fibrinogen, D-dimer, coagulation factor V (FV), coagulation factor VIII (FVIII), coagulation factor von Willebrandt (vWF) and other TGA parameters: lag time (LT), time to peak (TtP), and peak height (Ph). The gene discussed is F8; the disease is pulmonary arterial hypertension.