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Contraception - Background information
How does the combined contraceptive patch prevent pregnancy?
- Each 20 cm2 patch delivers 150 micrograms of norelgestromin (a progestogen) and 20 micrograms of ethinylestradiol (an oestrogen) daily into the systemic circulation. A 4-week cycle, with a new patch weekly for 3 weeks, and no patch for the fourth week, provides a similar hormonal pattern to that of combined oral contraceptives (COCs).
- The contraceptive actions of the combined contraceptive patch are therefore similar to those of COCs, i.e. mainly inhibiting ovulation [FFPRHC, 2004c]. For more information see Combined oral contraceptives.
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