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Contraception - Background information
How does the combined vaginal ring prevent pregnancy?
- The combined contraceptive vaginal ring delivers 15 micrograms of ethinylestradiol (an oestrogen) and 120 micrograms of etonogestrel (a progestogen) daily. A 4-week cycle, with a ring inserted vaginally for 3 weeks continuously, and no ring for the fourth week, provides a similar hormonal pattern to that of combined oral contraceptives (COCs).
- The main mechanism of action is inhibition of ovulation by suppression of gonadotrophins, together with secondary actions of alteration of cervical mucus and endometrium, inhibiting sperm penetration and implantation. For more information see Combined oral contraceptives.
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