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Hormonal methods for emergency contraception.

Raymond Hang Wun Li1, Sue Seen Tsing Lo1, Sharon Tracey Cameron2

  • 1Department of Obstetrics and Gynaecology, School of Clinical Medicine, The University of Hong Kong, Queen Mary Hospital, 102 Pokfulam Road, Pokfulam, Hong Kong; The Family Planning Association of Hong Kong, 10th Floor, 130 Hennessy Road, Wan Chai, Hong Kong.

Best Practice & Research. Clinical Obstetrics & Gynaecology
|September 7, 2024
PubMed
Summary
This summary is machine-generated.

Oral emergency contraception (EC) options include ulipristal acetate (UPA) and levonorgestrel (LNG). UPA offers higher efficacy than LNG, with both methods preventing pregnancy by delaying ovulation, not affecting implantation.

Keywords:
Cyclo-oxygenase inhibitorsHormonal emergency contraceptionLevonorgestrelMifepristoneUlipristal acetate

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Area of Science:

  • Reproductive Health
  • Pharmacology

Background:

  • Oral emergency contraception (EC) is crucial for reproductive health.
  • Ulipristal acetate (UPA) and levonorgestrel (LNG) are WHO-recommended oral EC methods.

Purpose of the Study:

  • To compare the efficacy and side effect profiles of UPA and LNG for emergency contraception.
  • To review the mechanisms of action and limitations of current oral EC methods.

Main Methods:

  • Review of existing literature on ulipristal acetate and levonorgestrel for EC.
  • Analysis of pharmacological actions, including ovulation inhibition and endometrial effects.
  • Evaluation of efficacy in different populations, such as women with higher BMI.

Main Results:

  • Ulipristal acetate (UPA) demonstrates superior efficacy compared to levonorgestrel (LNG).
  • Both UPA and LNG primarily work by inhibiting or delaying ovulation and do not prevent implantation.
  • LNG's effectiveness is reduced in women with a BMI over 26 kg/m² or weight over 70 kg.

Conclusions:

  • UPA is a more effective oral EC option than LNG with a similar side effect profile.
  • Mifepristone is an alternative EC but has limited availability.
  • Further research into LNG-releasing intrauterine devices and cyclo-oxygenase inhibitors for EC is warranted.