Currently, controlled ovarian stimulation (COS) in oocyte donors is performed by daily injections of gonadotropins( recombinant FSH) plus a GnRH Antagonist usually form 5th-6th stimulation day until ovulation induction with a bolus of another injection of a gonadotropin-releasing hormone (GnRH) Agonist. Injections of the GnRH Antagonist avoid untimely luteinizing hormone (LH) surge and spontaneous ovulation prior to follicular aspiration. There is a preparation of long-acting recombinant follicle stimulating hormone (rFSH= (corifollitropin alfa (FSH-CTP), Elonva®, MSD), that allows that a single subcutaneous injection substitutes the first 7 days of daily gonadotropin injections. On the other hand, a contraceptive oral progesterone only( Desogestrel, DSG) is available for contraception, avoiding the LH surge. It has been described the usefulness of orally administered medroxyprogesterone acetate, 10 mg to inhibit the endogenous LH surge in IVF patients during COS. In donors, by administering a single injection of FSH-CTP and oral desogestrel since the first menstruation day, the total number of injections administered is reduced and less discomfort is experienced without adverse impact on ovarian response. No description of the hormonal and ovarian response under this protocol has been published

* oral desogestrel since the first menstruation day, * a single injection of FSH-CTP on the 7th menstrual cycle day * routine monitoring of ovarian response with transvaginal ultrasound every second day until pre-ovulatory bolus of GnRH * Hormones measured on day of 7th menstrual cycle day , day of pre-ovulatory bolus of GnRH and the day after the bolus ( estradiol, FSH, Progesterone, LH) * Quality of Life questionnaire the day after the bolus