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Contraceptive efficacy and global licensing of 52 mg levonorgestrel intrauterine devices: does a Mirena last longer in New York than York?
  1. Zachary Nash1,2,
  2. Annette Thwaites2,3
  1. 1 Reproductive Medicine Unit, University College London Hospital, London, UK
  2. 2 EGA Institute for Women's Health, University College London, London, UK
  3. 3 Sexual and Reproductive Health, King’s College Hospital NHS Trust, London, UK
  1. Correspondence to Dr Zachary Nash, Department of Gynaecology, University College London, London WC1E 6BT, UK; z.nash{at}

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There is significant discrepancy between licensed durations for contraceptive efficacy of 52 mg levonorgestrel intrauterine devices (LNG-IUDs) across different countries and between UK licences and national recommendations (table 1). This is confusing and unhelpful for both clinicians and users.

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Table 1

Licensed durations for contraceptive efficacy of 52 mg levonorgestrel intrauterine devices

What is the discrepancy?

The 52 mg LNG-IUD is a highly effective, long-acting reversible method of contraception (LARC) offering additional therapeutic benefits to those with heavy menstrual bleeding or requiring endometrial protection as part of a hormone replacement therapy (HRT) regimen. Since the introduction of the Mirena® LNG-IUD 30 years ago,1 LNG-IUDs are now available in a variety of forms with different inserters, frame sizes, levonorgestrel (LNG) content and release rates.2

The Faculty of Sexual & Reproductive Healthcare (FSRH) intrauterine contraception guideline, published in March 2023, highlights that 52 mg LNG-IUDs are currently licensed in the UK for contraception for 5 years, Mirena®, or 6 years, Levosert®, two-handed device, and Benilexa®, one-handed device (marketed as Liletta® in the USA and Levosert® in some European countries) in women under the age of 45 years.2 During the COVID-19 pandemic, the FSRH temporarily recommended extended Mirena® contraceptive use to 6 years,3 4 and this change has been made …

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  • Contributors ZN and AT contributed equally to the conception and writing of this article.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.