 Participants eligible for this trial were oocyte donors 18-35 years of age, who had undergone controlled ovarian hyperstimulation in the long GnRH agonist protocol or the multiple-dose or single-dose GnRH antagonist protocols, had received hCG 5,000 IU urinary hCG or 250 μg recombinant hCG for triggering of final follicular maturation and had undergone oocyte retrieval with a yield of 6 cumulus-oocyte-complexes. Participants had given signed informed consent, were generally healthy and with a body mass index BMI of 18.5-29.9 kgm2. Participants were excluded in case of endometriosis stage I-IV or uterine pathology. Participants were willing to not have intake of alcoholic beverages during the trial, to not have sexual intercourse during the trial, and to either maintain sexual abstinence or use a highly effective method of contraception from end-of-trial till onset of next menses. 