 This was a randomised, double-blind, parallel groups, placebo-controlled, multi-centre trial. It was designed to evaluate the effects of a selective oxytocin antagonist barusiban and a mixed oxytocin antagonist - vasopressin V1a antagonist atosiban on uterine contractions during the luteal phase. Participants in this trial were oocyte donors who had undergone controlled ovarian hyperstimulation in the long gonadotrophin-releasing hormone GnRH agonist protocol or the multiple-dose or single-dose GnRH antagonist protocols, received hCG for triggering of final follicular maturation and undergone oocyte retrieval OR. The duration of the trial was five days and participants attended the clinic on three occasions: Day OR 1 screening, Day OR 2 randomisation and dosing of investigational medicinal product, and Day OR 5 end-of-trial. 