This study aims to study the efficiency of using a single injection of Corifollitropin alfa for ovarian stimulation by initiating administration late and without further administration of follicle-stimulating hormone after the 7th day of stimulation compared to conventional ovarian stimulation using Corifollitropin alfa (drug administration 5 days after cessation of hormonal contraceptive and supplementation with follicle-stimulating hormone daily administration from the 8th day of stimulation).

This a controlled randomized clinical study and 180 patients will be recruited (90 per arm) and the primary study outcome is the number of obtained oocytes.

Inclusion Criteria:

• Eligible for oocyte donation program
• Age between 18 and 32 years old
• BMI >18 and <30
• Antral follicle count >12 (summing both ovaries)
• Presence of both ovaries
• Ability to participate in and comply with study protocol
• Signed informed consent
• No treatment with ovulation stimulators in the 3 months prior to the start of stimulation.

Exclusion Criteria:

• Diagnosis of endometriosis at any stage
• AFC >20
• Polycystic ovary syndrome
• Concurrent participation in another study