Human Ovarian Follicular Dynamics and Emergency Contraception

Inclusion Criteria:

1. Female volunteers of childbearing potential;
2. Are first time users of oral contraception (OC) or have discontinued OC at least 1 month prior to study entry;
3. Age between 18 and 40 years old;
4. Normal body mass index (18-38);
5. Has signed informed consent form; and
6. Is in good health as confirmed by medical history, physical examination.

Exclusion Criteria:

1. A positive pregnancy test will automatically exclude the volunteer from participation in this study.
2. Any contraindication for oral contraception use;
3. Irregular menstrual cycles;
4. Ultrasonographic evidence of ovarian dysfunction, such as polycystic ovary syndrome (PCOS);
5. Pregnancy (suspected or diagnosed) or lactation;
6. History or suspicion of drug or alcohol abuse;
7. Participation in an investigational drug trial within the 30 days prior to selection;

8. 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.