Aside from a number of minor, but annoying, side effects, serious risks of BCPs are limited, for the most part, to cardiovascular problems, including stroke, heart attack, thrombophlebitis and thromboembolism.

These complications are rare among women under age 35 who are non-smokers and have no other high risk factors. The added risk of BCPs among these women is difficult to measure and probably insignificant.

For non-smokers over age 35, the increased risk of cardiovascular problems among BCP users is measurable, but small and certainly less than the risk of pregnancy.

For smokers under age 35, the increased risk of cardiovascular problems among BCP users is measurable, but small and certainly less than the risk of pregnancy.

For smokers over age 35, the increased risk of cardiovascular problems among BCP users is significant, and so high as to make such use ill-advised in any but the most extraordinary circumstances.

There is also a very small, but measurable increase in the risk of liver tumors and cysts. The incidence of such problems in the population is so small and the added risk so marginal that only rarely will this risk play a role in the clinical decision for or against BCPs.

One major problem in interpreting historical use of BCPs and their relative risks, is that the issue of ovarian suppression has not typically been addressed. This is important because those women whose BCPs have suppressed ovarian function will usually have reduced circulating sex hormone levels, while those whose BCPs have not suppressed ovarian function will usually have elevated circulated sex hormone levels. Since most studies involve a mix of these two groups of women, it is not possible to know with any degree of certainty whether the ovarian function suppressed women have less risk or more risk than those whose ovarian function is not suppressed.