Current perspectives on combination oral contraceptives

The physiology, mechanism of action, therapeutic use and effectiveness, potential risks, and noncontraceptive benefits of combination oral contraceptives (COCs) are reviewed with a discussion of patient considerations and management guidelines for common side effects. Modifications of the earlier COCs have both a lower estrogen and progestogen content. The contraceptive effects of estrogenic agents are related to modifications in ovulation, ovum transport, and implantation. The progestational agents act mainly by inhibiting ovulation and creating a hostile uterine environment. Biphasic and triphasic COCs are designed to deliver the hormones, throughout the menstrual cycle, in varying amounts that are similar to the natural physiologic quantities. The COC is the most effective method of birth control available with the exception of sterilization. If the low-dose COCs are taken at approximately the same time each day, they are as effective as 50-micrograms of estrogen in preventing pregnancy with a theoretical failure rate of less than 0.5 per 100 women-years. Three long-term cohort studies of the risks associated with COC use are described. Although the primary focus of early research was on the adverse effects of COCs related to estrogen content, recent studies indicate that there are some noncontraceptive benefits associated with the use of the low-dose COCs. In addition, the effects of progestogen content have been more closely examined in association with cardiovascular disease and metabolic effects. Guidelines for managing breakthrough bleeding and spotting, absence of withdrawal bleeding, nausea and vomiting, weight change, depression, and headaches are presented. Recommendations to give to women who are starting to take COCs for the first time are outlined. Low-dose COCs given at the appropriate dose can provide relatively safe and very effective contraception for many women.