This is a Phase 3, randomized, open-label, multicenter evaluation of the efficacy of a levonorgestrel-releasing intrauterine system (LNG20). The goals of the study include provision of information to understand efficacy and safety within the widest range of possible users of the LNG20. Typically, intrauterine contraceptive studies only include women 18-35 years of age for efficacy and safety, and place limits on parity and larger body size. Women outside of these characteristics also desire an effective intrauterine contraceptive. Accordingly, this study will include women who are both nulliparous and parous as well as women less than 18 years of age in the primary efficacy and safety analyses
