Mid-luteal Phase Synchronization of Ovarian Folliculogenesis in Women

Inclusion criteria

• female volunteers of childbearing potential;
• are first time users of OC or have discontinued OC at least 2 months prior to study entry;
• age between 18 and 35 years old;
• normal body mass index (18-30);
• has signed consent form; and
• is in good health as confirmed by medical history, physical examination

Exclusion criteria

• a positive pregnancy test will automatically exclude the volunteer from participation in this study.
• any contraindication for oral contraception use;
• known hypersensitivity to Letrozole and co-administered medications;
• irregular menstrual cycles;
• ultrasonographic evidence of ovarian dysfunction, such as Polycystic Ovary Syndrome (PCOS);
• history of pituitary tumor;
• HIV, HBV, HCV infection;
• vaginal infection;
• abnormal ECG;
• abnormal lab tests for blood profile, liver function and renal function;
• uncontrolled diabetes and blood pressure;
• pregnancy (suspected or diagnosed) or lactation;
• history or suspicion of drug or alcohol abuse;
• history of severe mental disorders;
• participation in an investigational drug trial within the 30 days prior to selection;
• exhibits a disorder that is a contraindication to steroid hormonal therapy, including, for example, the following conditions:

• history of, or actual, thrombophlebitis or thromboembolic disorders.
• history of, or actual, cerebrovascular disorders.
• history of, or actual, myocardial infarction or coronary artery disease.
• acute liver disease.
• history of, or actual, benign or malignant liver tumors.
• history of, or suspected, carcinoma of the breast.
• known, or suspected, estrogen-dependent neoplasia.
• undiagnosed abnormal vaginal bleeding.
• any ocular lesion arising from ophthalmic vascular disease, such as partial or complete loss of vision or defect in visual field.