 This study is a phase 2, 3-arm-study with an 18 week active dosing period and an option for subjects to receive 2 additional 16-week cycles of active treatment at their randomized dose 6 mg or 12 mgday. Placebo subjects who elect additional treatment will receive treatment at 12 mgday. The treatment dose will remain double-blind. The study will be conducted in 3 stages. In the first stage, women will receive a daily single-blind placebo. This stage will last as long as it takes to record at least one full menstrual cycle ovulation until ovulation. 