Birth control - slow release methods

Contraception - slow-release hormonal methods; Progestin implants; Progestin injections; Skin patch; Vaginal ring

Certain birth control methods contain man-made forms of hormones. The natural forms of these hormones are normally made in a woman's ovaries. These hormones are called estrogen and progestin.

Both of these hormones prevent a woman's ovaries from releasing an egg. The release of an egg during menstrual cycle is called ovulation. They do this by changing the levels of the natural hormones the body makes.

Progestin also helps prevent sperm from entering the uterus by making the mucous around a woman's cervix thick and sticky.

Birth control pills are one way of receiving these hormones. They are only effective if taken daily, preferably at about the same time.

There are other methods to prevent pregnancy. The same hormones may be used but they are released slowly over time.

Birth control methods

Artificial contraception methods work in different ways to decrease the likelihood that sexual intercourse will result in pregnancy. Barrier methods such as condoms (male or female), diaphragms (with or without spermicide) and sponges (with spermicide) have as their first line of defense the physical blocking of the sperm's entry into the uterus. If sperm cannot get into the uterus it cannot fertilize an egg, and pregnancy cannot occur. An IUD works in a different way, by making the uterus toxic to sperm and by disturbing the lining of the uterus so that it won't allow egg implantation. The hormones in oral contraceptives and hormone implants fool the ovaries into refraining from ovulation, and without a fertile egg, pregnancy will not occur. IUDs and oral contraceptives and hormones may be used as emergency contraception in the case of unprotected sex, but neither one will protect against sexually-transmitted disease.