The present prospective study was designed to compare the effects of administering a daily dose of gonadotrophin releasing hormone (GnRH) antagonist vs. an alternate-day dosage of GnRH agonist on ovarian response and in vitro fertilization (IVF) outcome in patients stimulated with recombinant follicle-stimulating hormone (FSH) and human chorionic gonadotrophin (hCG) microdose.

Inclusion criteria were as follows: women of good physical and mental health, under 37 years old, with regular menstrual cycles of 25-35 days, normal basal FSH and luteinizing hormone (LH) levels, body mass index (BMI) less than 30 kg/m2, presence of both ovaries and intact uterus, absence of polycystic ovaries, endometriosis, or gynaecological / medical disorders and a negative result in a screening for sexually transmitted diseases.

No patient had received any hormone therapy for at least 60 days preceding the study. Eligible patients who agreed to participate were randomized in two treatment groups. Patients were allocated to a GnRH analogue treatment group according to a computer-generated randomization table.

Inclusion Criteria:

• women of good physical and mental health
• under 37 years old, with regular menstrual cycles of 25-35 days
• normal basal FSH and LH levels
• BMI less than 30 kg/m2
• presence of both ovaries and intact uterus
• absence of polycystic ovaries
• endometriosis, or gynaecological / medical disorders and a negative result in a screening for sexually transmitted diseases
• all patients signed a written informed consent form
• no patient had received any hormone therapy for at least 60 days preceding the study.