Contraception is defined as the voluntary prevention of conception or impregnation.<sup>20   Webster's Seventh New Collegiate Dictionary Springfield, MA: G. & C. Merriam (1969). 

Haga clic aquí para ir a la sección de Referencias</sup> The various contraceptive medications and methods discussed in this issue have an amazing ability to prevent conception and impregnation, yet over 3 million unintended pregnancies occur in the United States each year. Half of these unintended pregnancies occur in women who use some type of contraceptive. The significant difference between method effectiveness (how well something works under ideal conditions) and use effectiveness (how well something works under typical conditions) can largely be attributed to compliance with the prescribed contraceptive regimens. This article examines the consequences of suboptimal contraceptive compliance, potential reasons for noncompliance, theories of health behavior, and potential strategies for improving compliance in individual patients.