Interventions
The "intervention" of contraception can be considered as the method itself and as the means by which family-planning clients obtain services (including counseling) and contraceptive commodities. Both the methods and the types of services are diverse.
Contraceptive Methods
Contraceptive methods can be classified as permanent and long term—primarily for those women and couples who have completed childbearing—or temporary—primarily for those women and couples who wish to delay pregnancy.
Permanent and Long-Term Methods
Female sterilization, or tubal ligation, used by about 187 million women worldwide (WHO 2002a), is the most popular and effective contraceptive available. The most effective types of female sterilization have a 10-year cumulative pregnancy rate of 7.5 per 1,000 procedures (Peterson and others 1996).
Sterilization accounts for one-third of all contraceptive practice. Because sterilization is considered a permanent form of contraception, some women may regret their decision during ensuing years. Some dissatisfaction with sterilization is expected and is always observed among sterilized populations; in most cases, the proportion of women regretting sterilization falls below 10 percent. Regret is higher when sterilization was a woman's first and only contraceptive method, when a woman was sterilized at or under age 30, or when a woman has fewer than four living children (Loaiza 1995).
Between 40 million and 50 million men worldwide have undergone a vasectomy, a figure representing 8 percent of the world's couples of reproductive age. This method comes in fourth in contraceptive popularity, after female sterilization (19 percent), the intrauterine device (IUD; 13 percent), and oral contraceptives ("the pill"; 8 percent), and right ahead of the male condom (4 percent; WHO 2002a). The method is as effective as female sterilization (failure rate of less than 1 percent) and much simpler and safer than tubal ligation.
The IUD is now used by 150 million women worldwide, or about 13 percent of the world's women of reproductive age, because of its efficacy, safety, and convenience. After female sterilization, it is the most popular method of contraception. The 5-year life span of the IUD means fewer visits to health providers and less expenditure of money, time, and effort.
IUDs prevent pregnancy through several mechanisms: they alter sperm migrations, inhibit fertilization, and generate a foreign-body reaction in the endometrium. Progestogen-releasing IUDs cause changes in the amount and viscosity of cervical fluid, altering sperm penetration. In a small percentage of women, ovulation is inhibited in the first two years of use. Failure rates for all copper-bearing IUDs are usually less than 1 per 100 women in the first year of use.
Temporary Methods
By far the most popular temporary contraceptive method is the oral contraceptive, commonly known as "the pill," which has a failure rate typical use of less than 10 percent over a year. Among 67 developing countries for which survey data are available (not including China or India), about 50 percent of married women who have ever used contraception have used the pill at some point. The pill has been most popular in Latin America; there, about 55 percent of all married women have used the pill. In the Near East and North Africa, about one-third of married women have used the pill, and in Sub-Saharan Africa, about 15 percent have used it at some time (Johns Hopkins Population Information Program 2000).
More than 20 million women use systemic contraceptives containing only progestins. These contraceptives include subdermal implants such as Norplant, injectable products, IUDs, and vaginal rings. These products have high rates of contraceptive efficacy (0.3 to 1.0 percent failure rate over 12 months). Their long duration of action allows for a relatively infrequent dose. Their main drawbacks are their tendencies to cause highly irregular endometrial bleeding and amenorrhea. Although altered bleeding does not have any ill health effects, it does pose a problem for women in societies that bar or restrict women from certain social and religious activities during menstruation. The World Health Organization estimates that between 10 and 30 percent of women abandon their progestin-only methods for this reason (WHO 2002a).
Barrier methods, although less effective than hormonal methods, IUDs, or sterilization, can offer effective contraception when used consistently and correctly. Barrier methods, and particularly condoms, are the only type of contraception that offers additional protection against STIs.
When used correctly during every act of sexual intercourse, the male latex condom is effective against both unwanted pregnancy and HIV infection and other STIs. Typical use results in pregnancy rates of 3 to 14 percent per year. If a condom breaks or tears during intercourse, emergency contraception can be used to reduce the risk of pregnancy.
The female condom, made of soft, pliable polyurethane and prelubricated with a silicone-based substance, is inserted into the vagina before sexual intercourse. The female condom is slightly less effective than the male condom, with a failure rate of 5 to 21 percent. Unlike the male condom, the female condom can be inserted up to eight hours before intercourse. The female condom adds to the arsenal of weapons in the fight against STIs; offers women more control in sexual negotiations; can be used in conjunction with the IUD, hormonal methods, and sterilization; and has no special storage requirements.
The diaphragm, although not a popular method in developing countries, is being studied as a means of preventing not only pregnancy but also bacterial STIs. Results from those randomized trials are pending.
Emergency Contraception
Since the mid 1960s, the use of certain oral contraceptives has been shown to be effective in preventing pregnancy. Two hormonal regimens have proved to be both safe and effective for emergency contraception: combined oral contraceptives and progestogen-only pills. Both can be taken for up to 120 hours after unprotected intercourse. Emergency contraception represents a second chance to prevent an unwanted pregnancy after unprotected sex, and it is particularly responsive to the needs of youths and of women who have been coerced into intercourse.
Despite the demonstrated safety and efficacy of emergency contraception, its acceptance by providers and the public, and its inclusion on the WHO's essential drug list, emergency contraception is not widely available in many developing countries (Langer and others 1999).
