Oral contraceptives and venous thromboembolism: an epidemiological review.

New epidemiological studies have demonstrated a higher risk of venous thromboembolism among users of oral contraceptives (OCs) with third-generation progestogens desogestrel or gestodene compared with users of OCs with second-generation progestogens levonorgestrel or norgestrel. As the absolute risk of venous thromboembolism among users of OCs in general is lower in the new studies than in previously published studies, and as several important potential confounders are not controlled for in the new studies, the real difference in risk of venous thromboembolism between users of third- compared with second-generation products may be smaller than indicated in these new studies. At the same time, the risk of myocardial infarction may be smaller among users of third- compared with users of second-generation products. Until further epidemiological data emerge, it is therefore difficult to make general recommendations other than to use OCs with a low estrogen dose, and to make individual recommendations based on age, individual wish, and individual risk factors.