Third-generation oral contraceptives and thromboembolism risk.

Recently, observational studies have suggested an increased risk of nonfatal venous thromboembolic complications in women using oral contraceptives (OCs) containing the third-generation progestins, gestodene and desogestrel. Because of the observational, rather than randomized, nature of these trials, the clinical relevance of these findings is difficult to interpret. Each study included one or more potential sources of bias. In particular, cases came almost exclusively from hospitalized patients with nonfatal venous thromboembolism, which represents only a minority of patients diagnosed with this condition according to current clinical practice. In the absence of a sound biologic rationale to explain the increased risk with third-generation OCs, and considering the potential sources of bias within the current studies, an alternative view argues against causality. Oral contraceptives remain safe and effective. Clearly, additional research is needed to determine the relationship between thromboembolic disease and the use of third-generation OCs. In the interim, women should be informed thoroughly with objective data on all risks associated with the use of OCs.