What Are the Benefits and Risks of Combined Oral Contraceptives?

Although contraceptive methods are not without risks, the risks tend to be small, and they are balanced by health benefits. The health benefits and risks of each method vary by the individual circumstances and the medical condition of the user. Careful counseling of users by family planning providers can reduce many potential risks.

Just as health conditions or behaviors in oral contraceptive (OC) users may increase their risk of cardiovascular disease (e.g., hypertension or smoking) so also the health status of a country determines whether there will be more deaths prevented or caused by OC use in the country. In fact, in many developing countries the risk of dying as a result of pregnancy dwarfs the risk of dying from either cancer or cardiovascular disease.

The table illustrates the approximate magnitude of the risk of death for each disease associated with OCs as well as the risk of death from pregnancy for women using no contraceptives at all in four regions of the world.

Use of oral contraceptives protects women against ovarian and endometrial cancers. The incidence of ovarian and endometrial cancer is half as high in OC users as in nonusers. OC users in Western countries have a rate of ovarian cancer that is 2 per 100,000 women aged 15-64, or approximately half the overall rate. The same holds for users in other parts of the world, although the rate of these cancers is even lower.

OCs have no overall effect on breast cancer; however several studies have indicated that long-term use (5 or more years) in young women increases their risk of breast cancer. Data from the WHO study of steroid contraceptives and breast neoplasia reported that 5 years of use in women under 25 years of age was associated with a 50% higher risk of breast cancer than in nonusers. In countries in Asia or Africa, this means that the mortality rate for women 15-44 who used the pill in their early years would be approximately 1.5 per 100,000 compared to 1 per 100,000 non-users.

There is no consensus yet on the risk of OCs on cervical cancer, although several studies which control for other potential causes of this cancer indicate that there may be approximately a 50%-100% increased risk in women who use OCs for 5 years or more. In countries with low mortality from cervical cancer, a 100% increase would mean that instead of having a death rate of 1 per 100,000, the rate would be 2 per 100,000 users - a very rare event. However, in countries with high mortality from cervical cancer, such as in the Latin American case, where rates are approximately 12 per 100,000 women, OC users would have a rate of 24 per 100,000.

An OC user may have two to four times the risk of a cardiovascular event compared to a non-user. This means that for Latin American users, the rate of cardiovascular disease in women 35-44 may rise from 4 per 100,000 to 8 or 16 per 100,000. In Asian or African countries, however, the rate would increase from 1 to 2 or 4 per 100,000 users.

In all cases with the exception of Western countries, mortality from pregnancy (estimated in simulations based on non-contraceptors with no access to induced abortion) is much higher than death from any of these diseases.

OCs are likely to have little adverse impact on women's mortality in countries in Asia or Africa. The high mortality from childbirth to women in these regions, especially among adolescent women, women with several children and women with other health problems, clearly outweighs the slight risk of cancer or cardiovascular disease related to OC use. However, in Western and Latin American countries the balance may be influenced by local patterns of maternal mortality and whether OCs are shown to be definitely associated with breast and cervical cancer.