On Day OR +2, participants were screened and subsequently randomised to barusiban or placebo. All participants received an intravenous (IV) bolus for 1 minute followed by an IV infusion for up to 59 minutes, administered via an indwelling catheter, of barusiban or placebo. Bolus volume and infusion rate were identical for barusiban and placebo. A mock embryo transfer (MET) procedure was performed 40 minutes after start of dosing and included intrauterine administration of a non-radioactive ultrasound contrast agent (SONOVUE) via the embryo transfer catheter. Transvaginal ultrasound of around 5 minutes duration was performed at seven time points on Day OR +2 and covered a span of approximately 2.5 hours including pre-dosing, during dosing, before and after mock embryo transfer, and post-dosing. The transvaginal ultrasound recordings were analysed for frequency of uterine contractions and other uterine contractility parameters by a central independent assessor, blinded to treatment allocation. Movement of the ultrasound contrast agent after the mock embryo transfer procedure was evaluated by the central independent assessor.