Random-start Ovarian Stimulation in Egg-donors (ROSE) (ROSE)

The purpose of this prospective single-center study is to evaluate the laboratory outcome after random start ovarian stimulation in oocyte donors. The study will be performed in egg-donors but this type of treatment has the potential to be implemented in general infertility population.

The study group will start ovarian stimulation randomly in different moments throughout the menstrual cycle. Randomization will take place on day 2-3 of the menstrual cycle, according to a list of random allocation of treatments and egg-donors will be assigned to random start ovarian stimulation: During follicular phase starting at day 5,7,9,11 or 13 of the menstrual cycle and during luteal phase starting at luteinizing hormone (LH) peak +3,+5,+7,+9 or +11. Egg-donors will receive urinary follicle stimulating hormone (FSH) 150-225 IU/d in gonadotropin-releasing hormone (GnRH) antagonist protocol with cetrorelix acetate 0,25 mg/d starting five days after ovarian stimulation and a GnRH agonist trigger with triptorelin 0,2 mg to induce the final follicular maturation. Transvaginal ultrasound and serum analysis (estradiol, progesterone, LH and FSH) will be included for cycle monitoring.

Egg-donors will be assigned to random start ovarian stimulation: During follicular phase starting at day 5,7,9,11 or 13 of the menstrual cycle and during luteal phase at luteinizing hormone (LH) peak +3,+5,+7,+9 or +11. They will receive urinary follicle stimulating hormone (FSH) 150-225 International units / daily (IU/d) and five days later the gonadotropin-releasing hormone (GnRH) antagonist: cetrorelix acetate 0,25 mg/d will be added until achieving criteria for receiving triptorelin 0,2 mg to induce final follicular maturation. Egg collection will take place 36 hours later. Interventions: Random start ovarian stimulation Gonadotrophins: Urinary FSH 150-225 IU/d GnRH antagonists: Cetrorelix 0,25 mg/d GnRH agonist for triggering: Triptorelin 0,2 mg single dose

Egg-donors will start ovarian stimulation randomly at different moments throughout the menstrual cycle.

When collected, eggs retain numerous cells (granulosa or cumulus cells) surrounding the oocyte; this structure is termed as the cumulus oocyte complex (COC). Few hours later (2-4 hs), the oocyte is denuded from these cumulus cells, allowing for a clearer observation of the maturity status (presence or absence of a metaphase II) of the oocyte. The percentage of mature eggs represents the proportion resulting from dividing the total number of COCs collected by the number of metaphase II oocytes and multiplied by 100.

Inclusion Criteria: Premenopausal women 18-35 years old FSH levels < 10 IU/liter Antral follicle count (AFC) > 10 Regular cycles Body Mass Index (BMI) < 28 Signed informed consent Exclusion Criteria: Polycystic ovary syndrome (PCOS) patients Allergy to gonadotrophins Concomitant participation in other trial