Contraceptive mechanism of microdose norethindrone.


To determine how microdose progestogens exert their contraceptive mechanism, 5 normal 20-40 year old women (each acting as her own control) were studied during a normal menstral cycle followed by a cycle in which each received orrally 350 mcg norethindrone per day beginning on Cycle Day 1 for 30 days. Results indicated that all control cycles were ovulatory. In the treated cycle, endometrial morphology was altered. There was also significant suppression of preovulatory FSH and LH peaks, alteration of urinary estrogens (either increase or decrease), and marked suppression of progesterone production during the luteal phase. Cervical mucus properties and sperm penetration were inhibited during the treatment cycle. These findings suggest that at least 3 different factors were involved in the contraceptive mechanism of microdose norethindrone: 1) alteration of ovulation and progesterone production by the corpus luteum, 2) cervical mucus changes and inhibition of sperm transport, and 3) endometrial's modified

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@article{Moghissi1973ContraceptiveMO, title={Contraceptive mechanism of microdose norethindrone.}, author={Kamran S. Moghissi and F N Syner and Lanamarie McBride}, journal={Obstetrics and gynecology}, year={1973}, volume={41 4}, pages={585-94} }