A flexible protocol for the induction of recipient endometrial cycles in an oocyte donation programme

Synchronization of the availability of good quality oocytesfrom donors and adequate endometrial maturation of recipientsare very important for the success of an oocyte donation programme.A flexible protocol for the endometrial preparation of recipientsis important in timing embryo transfer between days 17 and 19of the cycle (‘window of receptivity’). The purposeof this study was to evaluate the effect of the length of oestradioladministration to recipients on pregnancy outcome. Oestrogenadministration was 8 mg/day, but its length varied prospectivelyfrom 6 to 27 days, followed by the addition of progesterone(100 mg daily Lm.) for 2–4 days according to the availabilityof good quality oocytes. Pregnancy outcome was evaluated regardlessof age, indication for oocyte donation or number of embryostransferred per patient The pregnancy rate per cycle was comparablewhen oestradiol was administered from 6 to 11 days before progesteroneaddition, while it dropped significantly thereafter. The variationin progesterone administration did not affect pregnancy outcome.These findings provide us with a greater flexibility by allowingus to vary oestradiol administration to recipients from 6 to11 days prior to progesterone, reducing considerably, therefore,the need to cancel embryo transfer because of oocyte unavailability.Thus we can arrange to transfer embryos between days 17 and19 of the recipient's cycle so as to obtain the best possibleclinical outcome.