UC Davis

OBJECTIVE: To assess 6-year contraceptive efficacy and safety of a levonorgestrel 52 mg intrauterine system (IUS). STUDY DESIGN: We assessed pregnancy rates through 72 months in women aged 16-35 years at enrollment and safety in all participants (aged 16-45 years, n = 1751) in an ongoing 10-year phase-3 trial. RESULTS: Over six years, nine pregnancies occurred (none in year 6) for a life-table pregnancy rate of 0.87 (95% CI 0.44-1.70). Adverse event rates remain low through 6 or more years of use. Two expulsions occurred in year 6. CONCLUSION: This levonorgestrel 52 mg IUS is a highly effective and safe contraceptive over 6 years of use. IMPLICATIONS: The levonorgestrel 52 mg IUS shows high 6-year contraceptive efficacy and a low rate of adverse events through 6 or more years of use.