What is the mechanism of action for combination 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

Prevention of ovulation is considered the dominant mechanism of action. Either estrogen or progesterone alone is capable of inhibiting both FSH and LH sufficiently to prevent ovulation. The combination of the 2 steroids creates a synergistic effect that greatly increases their antigonadotropic and ovulation-inhibitory effects. They also alter the consistency of cervical mucus, affect the endometrial lining, and alter tubal transport.


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