Investigation of Female Reproductive Hormone Dynamics During Adolescence

Inclusion Criteria: * no more than 3 ½ years postmenarchal Exclusion Criteria: * Subjects currently on or previously treated with medications that may affect reproductive hormones (eg birth control pills). * Subjects with severe acne or hirsutism * Subjects who exercise excessively (running \> 20 miles/week or its equivalent) * Subjects with any of the following medical conditions: diabetes, hypertension, hyperlipidemia, valvular heart disease, lupus, rheumatoid arthritis, migraine headaches with aura, undiagnosed breast mass, inflammatory bowel disease, gallbladder disease, sickle cell disease, or thrombophilia. * Current smoker * History of deep venous thrombosis or pulmonary embolism in subject or first-degree relative