Fertility in Healthy Premenopausal Women

Inclusion Criteria: * Females, age ≥ 21 years * Premenopausal (defined as a woman that has had at least one menstrual cycle in the last 365 days). * A minimum weight of 110 lbs * The subject is not anemic (Hemoglobin ≥ 12.5 g/dL) * Willing to provide a daily blood draw for one ovulatory cycle or a maximum of 33 days * Able to understand and willing to provide informed consent. Exclusion Criteria: * Males * Females, age \<21 years * Weighing \< 110 lbs * Anemic (Hemoglobin \< 12.5 g/dL) * History of bilateral oophorectomy * Females taking any form of hormonal birth control including: * Oral contraceptive pill (combined or progestin-only) within five days enrollment. * Contraceptive patch (such as Ortho Evra®) within seven days of enrollment. * Vaginal contraceptive ring (such as NuvaRing™) within 21 days of enrollment. * Contraceptive injection (such as Depo-Provera®) within 90 days of enrollment. * Intra-uterine system (IUS) within 90 days of enrollment. An intra-uterine device (IUD) made of copper does not exclude the patient from participating in this study. * Subdermal contraceptive implants (such as Nexplanon®) within 90 days of enrollment. * Emergency contraceptive within 30 days of enrollment. * Women in menopause (defined as the end of menstrual cycles or at least more than 365 days since the last menstrual cycle) * Amenorrhea except for women that continue to ovulate as documented in a physician note available to the enrolling center. * Has a current diagnosis of any clinically significant cardiac, respiratory, neurological, immunological, hematological, liver disease, renal disease, gastrointestinal (GI) disorder, including any history of hyper- or hypothyroid, peptic or gastric ulcers or GI bleeding, or any other condition which, in the opinion of the investigator, would deem the subject unhealthy and therefore, ineligible. * Has a history of any clinically significant cardiac, respiratory, neurological, immunological, hematological, liver disease, renal disease, gastrointestinal (GI) disorder, including any history of hyper- or hypothyroid, peptic or gastric ulcers or GI bleeding, or any other condition which, in the opinion of the investigator, is unstable at the time of enrollment. * Is receiving systemic chemotherapy or radiation treatment, has an active malignancy of any type, or has been diagnosed with cancer within 5 years before screening other than basal or squamous cell skin cancers or in-situ cervical cancer. * History of seizures * Diagnosed with an infectious disease including any sexually transmitted diseases. * Diagnosed with HIV/AIDS or ever tested positive for HIV. * History of hepatitis * Subject that has had sexual contact with a person who has hepatitis within the last 12 months. * Pregnancy, lactation or actively seeking to conceive (trying to become pregnant). * Unable to provide informed consent.