An open-label study to assess the PK of estradiol, estrone and progesterone from the DARE-HRT1 intravaginal rings at two different dose strengths.

Inclusion Criteria:

• Postmenopausal women with body mass index >/= 18 and </= 38 kg/m2
• Normal cervix and vagina
• An intact uterus
• An acceptable results from an endometrial biopsy
• normal mammogram report within 24 months of screening

Exclusion Criteria:

Prior abnormal cervical screening test (CST) or Pap result within 2 years of screening. Subject can have atypical squamous cells of undetermined significance (ASCUS), if HPV negative.

Subjects with any self-reported active sexually transmitted disease and/or evidence of infection based on visual vaginal exam by the investigator

Subjects with a UTI during screening as assessed by urine dipstick test with abnormal test findings (any positive result for leukocytes AND any positive result for nitrites)

Subjects with > 4 mm endometrium lining at screening (on the transvaginal ultrasound)

Have a history of endometrial hyperplasia or cervical or uterine carcinoma

Subjects with indwelling catheters or requiring intermittent catheterization

Subjects with multiple or unsuccessful (e.g., still having symptoms) pelvic reconstructive surgery, or suffers from pelvic relaxation

Subjects who have had a hysterectomy

Subjects taking any estrogen and/or progesterone products (see Section 4.1 for washout requirements)

Subjects with concomitant use of personal lubricants (water-based lubricants are allowed) or any intravaginal product or medication, either by prescription or over-the-counter (e.g., Femring [estradiol acetate vaginal ring], ESTRING® [estradiol vaginal ring]) with the exception of those who agree not to use these products during the IVR use period

Self-reported or observed vaginal irritation; vaginal, vulvar, or cervical lesions, undiagnosed vaginal bleeding; or tenderness

Subjects with a finding of clinically significant uterine fibroids at screening

Subjects with a known hypersensitivity to progesterone, estradiol, Femring, or the components of the IVR (e.g., ethylene vinyl acetate)

Subjects with known hypersensitivity to peanuts (Prometrium capsules contain peanut oil)

Subjects with prior pelvic malignancies

Subjects with a history of any severe acute or chronic medical or psychiatric condition or laboratory abnormality that could increase the risk associated with trial participation or study treatment administration or could interfere with the interpretation of trial results and, in the judgment of the investigator, would make the subject inappropriate for entry into the trial. This includes but is not limited to the following:

Human immunodeficiency virus (HIV) infection (confirmed by medical history/ serology testing)

Active chronic hepatitis B or hepatitis C infection including hepatitis B surface antigen and hepatitis C antigen positive subjects with or without abnormal liver enzymes (confirmed by medical history/serology testing)

Concurrent neurodegenerative disease

Cardiovascular: uncontrolled hypertension, unstable angina, myocardial infarction or symptomatic congestive heart failure within the past 6 months, serious uncontrolled cardiac arrhythmia, use of Class 1 antiarrhythmic medications, or history of venous thromboembolism or stroke

Dementia or significantly altered mental status that would prohibit the understanding or rendering of informed consent and compliance with the requirements of the protocol

History of gallbladder disease unless gallbladder removed

Symptomatic bacterial vaginosis

Have fasting triglyceride of > 300 mg/dL and/or total cholesterol of > 300 mg/dL

AST or ALT > 1.5 times the upper limit of normal

Fasting glucose > 125 mg/dL

Evidence of current alcohol or drug abuse in the past 60 days including a positive result from the urine drugs of abuse or alcohol screen, or history of drug or alcohol dependence in the last two years, as assessed by principal investigator. Alcohol abuse is defined as greater than 14 standard units/week for females and drug abuse is defined as known psychiatric or substance abuse disorder that would interfere with participation with the requirements of this study, including current use of any illicit drugs.

Participation in any other investigational drug or device trial in which administration of an investigational study drug/device occurred within 30 days or placement of a non-drug eluting medical device within 15 days prior to screening.

Must be female.

PI unable to publish trial results after the trial is completed without prior approval from Sponsor.