Additional Study Information: The study is looking to evaluate levonogestrel butanoate as a possible new long-acting injectable for birth control. Levonogestrel butanoate is a type of hormone called progestin that has a long history of clinical use in a variety of birth control methods (e.g. pills, intrauterine devices, implants) and its efficacy and safety are well recognized. This study is seeking for healthy female volunteers between the ages of 18-40 years of age. Participation time is estimated to last up to 9 months with approximately 36 study visits. The first visit will last about 1 hour and all other visits will typically last about 30-45 minutes with the exception of visit 3 that is expected to last 8-10 hours. Study visits will vary but mostly consist of physical and gynecological exams, transvaginal ultrasounds, urine pregnancy test, and blood draws.