Effects of Hormonal Contraceptives on Liver Proteins and Coagulation Factors: A Comparison of a Contraceptive Vaginal Ring and an Oral Contraceptive

Inclusion Criteria: * Healthy women, aged 18-34 years, who did not wish to become pregnant for 3 months (or 5 months if first discontinuing oral contraceptives * Intact uterus and at least 1 ovary * Have regular menstrual cycles (28 ± 7 days) or 2 regular cycles after parturition or abortion * Willing to use condoms while having sexual intercourse during the 3 month study (or 5 months if discontinuing oral contraceptives), or * Willing to continue use of a specified non-hormonal method of birth control including permanent sterilization, non-hormone-containing IUD, male condoms, or abstinence during the study or to use condoms if discontinuing one of these methods * Willing and able to comply with the protocol * Willing and able to sign informed consent prior to entry into the study and prior to discontinuing another method of contraception * Easy venous access Exclusion Criteria: * Pregnancy * Known hypersensitivity to estrogens or progestins * Known hypersensitivity to silicone rubber * Undiagnosed vaginal discharge or vaginal lesions or abnormalities * Smoking status: \>15 cigarettes per day * Breastfeeding * Current or past thrombophlebitis or thromboembolic disorders * Family history of venous thrombosis or embolism (1st degree relatives \<55 years of age) * Known history of Factor V Leiden or positive screening test for APC-resistance * Current or past cerebrovascular or coronary artery disease * Carcinoma (hormone-dependent tumor; past history of any carcinoma not in remission for \>5 years) * Medically diagnosed severe depression * Headaches with focal neurological symptoms * Undiagnosed abnormal genital bleeding * History of cholestatic jaundice of pregnancy or jaundice with prior steroid use * Benign or malignant liver tumors; active liver disease * Diastolic/systolic BP ≥90/140 mmHg after 5 min. rest * Known or suspected alcoholism (\>2 drinks/day)or drug abuse * Positive for hepatitis B \& C and/or HIV 1 or 2, abnormal screening CBC, serum chemistry values (including fasting, total cholesterol and triglycerides), abnormal Pap smear, abnormal findings on dipstick urinalysis, or an abnormal electrocardiogram (ECG) * Participation in a clinical trial within last 3 months or more than 1 trial in the last year * BMI (kg/m2) \>28 * Use of injectable contraceptives in last 6 months (e.g. cyclofem or DMPA) * Unwilling to stop oral contraceptives for 2 months prior to study initiation * Use of implanted hormonal contraceptives, including Mirena or Implanon, in last 2 years * Not living in the catchment area of the clinic\*Severe cystoceles or rectoceles