Oral contraceptives come in a variety of formulations. The main division is between combined oral contraceptive pills, containing both estrogen and synthetic progesterones (strictly progestins, but the former term is used in medical conext), and progesterone only pills (mini-pills). Combined oral contraceptive pills also come in varying types, including varying doses of estrogen, and whether the dose of estrogen or progesterone changes from week to week. How they work Combination pills u ...
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