The patient population will consist of 750 infertile women with PCOS with ovulatory dysfunction and either one of the remaining two criteria, hyperandrogenism (clinical or biochemical) or polycystic ovaries on ultrasound, with exclusion of secondary causes of PCOS. Additionally, the couple will have no other major infertility factor, and the subject will have at least one patent fallopian tube and a normal uterine cavity, and a partner with a sperm concentration of 14 million/mL in at least one ejaculate.

Inclusion Criteria:

• Key Inclusion Criteria (Must have ovulatory dysfunction and either hyperandrogenism or PCO)

  1. Chronic anovulation or oligomenorrhea: defined as spontaneous intermenstrual periods of ≥45 days or a total of ≤8 menses per year, or for women with suspected anovulatory bleeding, a midluteal serum progesterone level < 3 ng/dL is indicative of chronic anovulation. For women who have been on ovarian suppressive therapy or other confounding medication (i.e. insulin sensitizing agents) within the last year prior to the study, a history of ≤8 menses per year prior to the initiation of this prior therapy will qualify as evidence of oligomenorrhea. For women with more regular bleeding patterns, but who are suspected to be experiencing anovulatory bleeding, a midluteal progesterone level < 3ng/dL will be evidence of ovulatory dysfunction and qualify as anovulation.

  2. Hyperandrogenism (either Hirsutism or Hyperandrogenemia) or Polycystic Ovaries on Ultrasound:

     1. Hirsutism is determined by a modified Ferriman-Gallwey Score >8 at screening exam (Hatch, Rosenfield et al. 1981 Aug 1). Subjects who have hirsutism do not need local or core labs documenting elevated androgen levels.
     2. Hyperandrogenemia will be defined as an elevated total testosterone, or free androgen index (FAI). Outside lab values obtained within the last year documenting elevated T or FAI levels are sufficient to meet criteria of hyperandrogenemia.
     3. Polycystic Ovaries on Ultrasound: PCO will be defined as either an ovary that contains 12 or more follicles measuring 2-9 mm in diameter, or an increased ovarian volume (> 10 cm3) on one ovary for entry into the study. If there is a follicle > 10 mm in diameter, the scan should be repeated at a time of ovarian quiescence in order to calculate volume and area if the subject does not otherwise qualify for the study. The presence of a single polycystic ovary (PCO), either by volume or morphology, is sufficient to provide the diagnosis.

Exclusion Criteria:

• We will exclude subjects with medical conditions that represent contraindications to CC, aromatase inhibitors and/or pregnancy or who are unable to comply with the study procedures. We will exclude subjects with poorly controlled Type 1 or 2 diabetes; undiagnosed liver disease or dysfunction (based on serum liver enzyme testing); renal disease or abnormal serum renal function; significant anemia; history of deep venous thrombosis, pulmonary embolus, or cerebrovascular accident; uncontrolled hypertension, known symptomatic heart disease; history of or suspected cervical carcinoma, endometrial carcinoma, or breast carcinoma; undiagnosed vaginal bleeding, and use of other medications known to affect reproductive function or metabolism (e.g., OCP, GnRH agonists and antagonists, anti-androgens, gonadotropins, anti-obesity drugs, somatostatin, diazoxide, ACE inhibitors, and calcium channel blockers). As in PPCOS we will allow a 3 mos washout period for subjects who desire to participate and discontinue exclusionary medications (most commonly OCP, but also possibly metformin), and a period of observation or treatment for correctable conditions.