What is the recommended duration of use for Mirena (levonorgestrel-releasing intrauterine system)?

Mirena Duration of Use

Mirena (52 mg levonorgestrel-releasing intrauterine system) is FDA-approved for 5 years but maintains high contraceptive efficacy for up to 8 years, with a cumulative failure rate of only 0.68% during years 6-8. 1, 2, 3

Current FDA Approval vs. Extended Use Evidence

• The 52 mg levonorgestrel IUD (Mirena) carries official FDA approval for 5 years of contraceptive use 1
• However, robust clinical trial data demonstrates that Mirena retains contraceptive effectiveness extending to 8 years of continuous use 1, 2, 3
• The Mirena Extension Trial, a multicenter U.S. study, specifically evaluated efficacy beyond the initial 5-year approval period in women aged 18-35 years 2

Contraceptive Efficacy During Extended Use

Years 6-8 Performance Data

• The 3-year Pearl Index for years 6-8 was 0.28 (95% CI: 0.03-1.00), with only 2 pregnancies occurring among 362 participants 2
• The cumulative failure rate for years 6-8 was 0.68% (95% CI: 0.17-2.71), comparable to the failure rates reported during the first 5 years 2, 3
• Individual year Pearl Indexes were: Year 6 = 0.34, Year 7 = 0.40, Year 8 = 0.00 2

Safety Profile During Extended Use

• Treatment-emergent adverse events occurred in 68.8% of participants during years 6-8, with only 18.0% considered device-related 2
• The ectopic pregnancy Pearl Index for years 6-8 was 0.14 (95% CI: 0.00-0.77) 2
• User satisfaction remained exceptionally high, with 98.7% of women who completed 8 years reporting satisfaction with continued use 2

Clinical Implications for Practice

Bleeding Patterns with Extended Use

• During years 6-8, women experienced a continued decrease in mean bleeding or spotting days 2
• Approximately 50% of women reported amenorrhea or infrequent bleeding during extended use 2
• At 6 months of initial use, 44% of women report amenorrhea, increasing to 50% at 12 and 24 months 4

Return to Fertility

• Among women who discontinued Mirena early due to desire for pregnancy, the 12-month return-to-fertility rate was 77.4% 2
• Fertility returns rapidly after device removal 1

Important Caveats

Heavy Menstrual Bleeding Indication

• The extended use data (beyond 5 years) applies specifically to contraception 2
• Insufficient numbers of women were enrolled in the extension trial to assess efficacy for heavy menstrual bleeding beyond 5 years 2
• For heavy menstrual bleeding, Mirena remains a first-line medical management option alongside oral contraceptive pills, but the evidence supports only the FDA-approved 5-year duration for this indication 1

Discontinuation Considerations

• The discontinuation rate during years 6-8 was 38.4%, most commonly due to desire for pregnancy (12.2%) 2
• Removals due to menstrual bleeding problems are concentrated in the first 6 months of use, primarily from amenorrhea or menorrhagia 4
• Women should be counseled that device removal is available at any time if they find bleeding patterns or other side effects unacceptable 5

Patient Selection for Extended Use

• The extension trial enrolled women aged 18-35 years who had used Mirena for 4.5-5 years, with all participants ≤36 years at the end of year 8 2
• Just over half of participants were parous 2

Practical Recommendation

For contraception alone, counsel patients that Mirena can be safely continued for up to 8 years based on high-quality clinical trial evidence, though FDA approval remains at 5 years. 2, 3 For heavy menstrual bleeding management, adhere to the 5-year FDA-approved duration due to lack of extended-use data for this indication. 1, 2