What is the efficacy of progestin-only oral contraceptives?

Updated: Oct 16, 2019
  • Author: Frances E Casey, MD, MPH; Chief Editor: Richard Scott Lucidi, MD, FACOG  more...
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Answer

Answer

Serum progestin levels peak approximately 2 hours after administration. Within 24 hours, rapid distribution and elimination returns the level to baseline. Greater efficacy is achieved with consistent administration.  Failure rates with typical use are estimated to be 7% in the first year of use. However, any variation can increase the failure rate.


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