The Food and Drug Administration (FDA) has approved the supplemental New Drug Application (sNDA) for Mirena (levonorgestrel-releasing intrauterine system), extending the duration of use for up to 8 years of pregnancy prevention. Previously, the intrauterine device was indicated for contraception for up to 7 years.

Mirena contains 52mg of levonorgestrel, which initially releases at a rate of approximately 21mcg/day. This rate decreases progressively to approximately 11mcg/day after 5 years and 7mcg/day after 8 years. By the end of the 8th year, Mirena should be removed and replaced at the time of removal with a new system if continued use is desired.

The approval was based on data from the phase 3 Mirena Extension Trial ( Identifier: NCT02985541) that evaluated the efficacy of Mirena during extended use beyond 5 years. The study included 362 women aged 18 to 35 years who had been using Mirena for not less than 4.5 years and not more than 5 years at enrollment. The primary endpoint was the pregnancy rate calculated as the Pearl Index (PI). 

Results showed that the PI for the 8th year of use was 0.00 with a 95% upper confidence limit of 1.90 based on no pregnancies that occurred during year 8 and within 7 days after Mirena removal or expulsion and 2534 evaluable cycles. The cumulative 3-year pregnancy rate for years 6, 7 and 8 was 0.68% with a 95% upper confidence limit of 2.71% based on 2 pregnancies (1 in year 6 and 1 in year 7) and 10,216 exposure cycles.

Mirena is also indicated for the treatment of heavy menstrual bleeding for up to 5 years in women who choose to use intrauterine contraception as their method of contraception. For this indication, it should be replaced after the end of the fifth year if continued treatment of heavy menstrual bleeding is needed.


  1. FDA label update reflects Bayer’s commitment to providing options for long-acting contraception. News release. Bayer. Accessed August 18, 2022.
  2. Mirena. Package insert. Bayer; 2022. Accessed August 18, 2022.