The baseline incidence of PPH (without oxytocin) and the proportion of PPH that are severe were estimated from published literature.[1,5,9,26] We assumed that AMTSL reduced the rate of PPH by 50% based on Begley et al[7] and that this effect was mainly attributable to the use of oxytocin, as has been shown in a trial comparing AMSTL vs oxytocin alone.[7,59,60]. This evidence concerns the gene OXT and pulmonary arterial hypertension.