Contraception means preventing pregnancy. There are many ways women can prevent pregnancy—they range from refusing to have sex (being celibate), to using a physical barrier (such as a condom for a man or woman, diaphragm or cervical cap) plus a spermicide, to an operation that "ties" the fallopian tubes preventing fertilization of the egg and causing permanent sterility. (Note—researchers have now learned that risks for ovarian cancer arise in the tubes therefore any woman choosing tubal sterilization should request tubal removal.) Most contraception is reversible but tubal removal or ligation and vasectomy are not.
There are two basic kinds of contraception: those that rely on high hormone levels to disrupt reproductive hormonal cycles and those that don't. Hormonal contraception is traditionally in the form of "The Pill" but today combined hormonal contraception (CHC, combined estrogen and a progestin) usually for 21 of 28 days, can be a pill, a patch or a vaginal ring. The CHC hormone levels, although called "low dose" must be high enough to interfere with normal menstrual cycle hormones, ovulation and preparation of the lining of the uterus for implantation. The common CHC dose of 20 microgram ethinyl estradiol is approximately four times higher than natural menstrual cycle estradiol levels. CHC must be taken reliably to be effective, disturbs cyclic hormones, carries a risk of blood clotting and may cause adolescent bone loss. The progestin-only pill is also a possibility—it is taken daily, is an androgenic (male-hormone-like) progestin and often gives irregular bleeding. Hormones are sometimes part of intrauterine devices (IUD) as in the levonorgestrel (an androgenic progestin) IUD used to decrease heavy bleeding in perimenopause. Depo-MPA (sometimes called Depo-Provera) is 3-monthly high dose injection of a non-androgenic progestin—its advantages are its effectiveness, 3-months duration and its disadvantages are weight gain and depression.
Non-hormonal reversible contraception uses a diaphragm or a condom as a physical barrier and always requires simultaneous insertion of vaginal spermicide. These methods cause no hormonal disruption, can be quite effective contraception, prevent sexually transmitted diseases but are of little value if not consistently and conscientiously used. Copper IUDs are also a long-acting, effective, non-hormonal contraception that can now be chosen by nulliparous or young women. They are highly effective and have few serious adverse effects.