Human Menopausal Gonadotropin (HMG) vs Recombinant Follicle Stimulating Hormone (rFSH) in Gonadotropin Releasing Hormone (GnRH) Antagonist Cycles

Inclusion Criteria: * women with good physical and mental health * aged 18-37 years * regular menstrual cycles ranging from 25 to 35 days; body mass index (BMI) \< 30 kg/m2 * normal basal serum FSH (≤ 10 IU/L) and E2 (≤ 75 pg/mL) levels determined on the day 3 of the cycle previous to COH * no uterine (fibroids, adenomyosis, mullerian malformations), ovarian (endometrioma, polycystic ovaries) or adnexa (hydrosalpinx) abnormalities assessed by vaginal ultrasound. Exclusion Criteria: * patients with a history of recurrent pregnancy loss * any significant systemic disease, endocrine or metabolic disorder * having concomitant medication interfering with the purposes of the study * patients who have received any ovulation induction drug within one month before their inclusion in the study.