Numerous recent media reports highlight the historic progress in women's health with development and marketing of oral contraceptives. As Collins reported in the New York Times (column), we celebrate the 50th anniversary of the birth control pill. She notes the need for information on contraception and the challenges women had historically obtaining accurate data. Over the past 50 years much research has focused on contraceptives methods their risks and benefits. As we have noted previously, benefits of oral contraceptives can be substantial. Media attention, however, often focuses on potential adverse effects such as venous thrombosis and pulmonary embolism, the benefits of prevention are not identified at the individual level and hence often ignored.
Contraception avoids not only unintended pregnancies, but also millions of abortions and many pregnancy related deaths. These global benefits are detailed in a report from the Alan Guttmacher Institute in New York. (report). US data indicate that among women 15 to 49 years of age 72.8% are using a method of contraception, 21.2 % repot female sterilization, 9.7% male partner sterilization, and 18% are using contraceptive pills (report).
A rigorous systematic review of contraceptive methods and effectiveness shows that failure varies by approach and by the level of adherence to “perfect use” (review). Combining data from epidemiologic studies show significant reduction in risk of ovarian cancer, endometrial cancer and colon cancer as well as dysfunctional uterine bleeding, and ovarian cysts.
Risk of ovarian cancer is reduced by 20 percent for each 5 years of use. After 15 years of use a woman’s risk is half that of what it would be if she had never user the contraceptive pill. The benefit of reduced ovarian cancer persists after stopping use.
The combined evidence shows without doubt that the pill is safe and has major benefits including a reduction in the level of cancer among users. Like many other prevention benefits, particularly those for cancer, the time course is long and the beneficiaries are largely unknown. This time to benefit clearly contrasts with the immediate benefit related to the indication for using the pill - avoidance of conception – a benefit that is observed each month.