Oral birth control (contraceptive) pills are used to prevent pregnancy. According to the American Congress of Obstetricians and Gynecologists, they are used by millions of women in the United States and are considered safe and effective for most women.
The pills work by suppressing ovulation, the release of eggs from the ovary. They also alter the lining of the womb to discourage implantation and alter the mucus in the cervix, the opening from the vagina to the womb, to prevent the entry of sperm cells.
The pills are derived from estrogen and progesterone, the two principal female sex hormones. The different types are formulations containing diverse combinations or single components.
Combination Pills
Combination pills contain an estrogen and a synthetic form of progesterone called a progestin. There are various combinations of these two components that provide a wide variety of brands and choices for women. They come in various dosing styles to fit different lifestyles and preferences.
Some of the combinations include: ethinyl estradiol (estrogen) and norethindrone (progestin) in Ovcon, Norinyl, Ortho-Novum, Necon, Nortrel, Brevicon, Modicon, Loestrin, Microgestin, Estrostep and Tri-Norinyl; ethinyl estradiol and levonorgestrel in Levlen, Levora, Nordette, Portia, Alesse, Aviane, Lessina, Levlite Enpresse, Tri-Levlen, Triphasil and Trivora-28; ethinyl estradiol and norgestrel in Ovral, Ogestrel, Lo/Ovral and Low-Ogestrel; ethinyl estradiol and desogestrel in Apri, Desogen, Ortho-Cept, Kariva, Mircette and Cyclessa; ethinyl estradiol and norgestimate in Ortho Tri-Cyclen and Ortho-Cyclen; ethinyl estradiol and drospirenone in Yasmin; ethinyl estradiol and ethynodiol in Demulen and Zovia.
Progestin-Only Pills
These are also called mini-pills. According to the American Congress of Obstetricians and Gynecologists, these birth control pills are the preferred choice in women with previous medical problems like blood clots, or in women with serious side effects from the combination pills and those still breast feeding. They are taken in cycles of 28 pills with care not to miss a dose.
The common progestin-only pills are nor-ethindrone (Micronor and Nor-Q.D.) and norgestrel (Ovrette).
Emergency Contraception Pills
These are also called the "morning after" pills and are employed in cases of rape or failure in other modes of contraception. They are typically taken within 72 hours of the episode of unprotected sexual intercourse. According to the National Institutes of Health, the only contraceptive pill that is FDA approved for emergency contraception is Plan B, which contains two tablets of higher doses of levonorgestrel than is usually seen in contraceptive pills. Other combination contraceptives taken in higher doses are also sometimes used in emergencies.
