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Levonorgestrel and mifepristone in emergency contraception
Helena von Hertzen1, Gilda Piaggio
1UNDP/UNFPA/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction, World Health Organization, Geneva, Switzerland. vonhertzenh@who.int
Steroids
|December 12, 2003
Summary
Two new emergency contraception methods, levonorgestrel and mifepristone, effectively prevent pregnancies. Mifepristone use is linked to a delayed return of menstruation compared to levonorgestrel.
Area of Science:
- Reproductive Health
- Pharmacology
Background:
- The World Health Organization's Special Programme of Research, Development and Research Training in Human Reproduction has pioneered new emergency contraception technologies.
- Two key methods have emerged: a levonorgestrel regimen and a low-dose mifepristone regimen.
Purpose of the Study:
- To review research on new emergency contraception methods.
- To present combined efficacy data for mifepristone and levonorgestrel from multinational trials.
- To compare the efficacy and side effect profiles of both regimens.
Main Methods:
- Systematic review and meta-analysis of multinational trial data.
- Inclusion of data from 6283 women in mifepristone groups and 4098 women in levonorgestrel groups.
- A randomized, double-blind trial comparing mifepristone and levonorgestrel, including a 1.5 mg levonorgestrel dose.
Main Results:
- Both levonorgestrel and mifepristone demonstrate high efficacy in preventing pregnancies when used shortly after coitus.
- Levonorgestrel has been approved in approximately 95 countries within 4 years.
- Mifepristone use was associated with a later return of menses compared to levonorgestrel.
Conclusions:
- Levonorgestrel and mifepristone are effective options for emergency contraception.
- The choice between methods may consider factors such as menstrual cycle regularity.
- Further research supports the widespread adoption of these emergency contraceptive methods.