7 also must take into account the limited duration of pregnancy-related risks. In addition, most studies of contraceptives have been carried out among women from developed countries. Nevertheless, the substantial volume of studies conducted in developing countries and the far larger risks of childbearing in those :.ountries, make clear the substantial impact of contraception in reducing both maternal morbidity and mortality. Brief summaries for each major type of contraception follow.

# Combined Oral Contraceptives

Overall, from a public health perspective and for most women, combined oral contraceptives provide health benefits which exceed the health risks. The benefits include protection against pelvic inflammatory disease, ectopic pregnancy, benign breast disease and ovarian cysts (Ory, 1982). In addition, this method relieves many menstrual disorders and helps to prevent iron-deficiency anemia. According to WHO and the International Planned Parenthood Federation, combined oral contraceptives remain a safe and highly effective contraceptive method for most women.

The most important health concern about this method is that it might increase the risk of cancer. The best epidemiological evidence is that it protects against endometrial and ovarian cancer, has no effect on breast cancer and has slight, if any, effect on cervical cancer. Studies of risks of malignancy and its determinants are complicated by the importance of sexual and other behavior as determinants and the difficulty of measuring those behaviors. Other specific, but usually rare, health risks from using oral contraceptives are those of circulatory complications and a rare liver cancer. The most important way to reduce these risks is for a woman not to smoke tobacco and to use oral contraceptives only for spacing. Finally, this method may reduce the volume of breast milk and usually should not be used by lactating mothers.

# Long-acting Injectables and Implants

These contraceptive methods do not contain the estrogen in combined oral contraceptives that is thought to cause the circulatory complications (Population Reports, 1975). Injectables do not reduce breastmilk volume and in addition confer similar health benefits to those of combined oral contraceptives. Injectable contraceptives cause menstrual disturbances and may contribute thereby to iron-deficiency anemia. They have been linked to malignant tumors in laboratory animals but there is only tenuous evidence from epidemiological studies of an increased risk in humans.

# The Intrauteline Device (IUD)

Overall, the IUD is an effective and relatively safe contraceptive method, especially for older women and those at any age in stable monogamous relationships. However, the IUD increases the rLsk of pelvic inflammatory disease, and thus the attendant risks of ectopic pregnancy and secondary infertility. This increased risk occurs at insertion and may be reduced by greater care to avoid use in infected women and by better insertion technique. Prophylactic antibiotics at insertion are also being evaluated. The IUD should normally not be used by women who have not borne children, because of the risk of infertility. By lowering the risk of pregnancy, the IUD reduces the overall risk of ectopic pregnancy. IUDs frequently cause