Why prospectively randomized clinical trials have been rare in reproductive medicine and will remain so?

There is almost unanimity that modern medicine should be "evidence based." In this context, lack of prospectively randomized clinical trials (RCTs) is widely lamented in reproductive medicine. Some leading voices, indeed, increasingly suggest that only RCT-based clinical conclusions should be integrated into clinical practice, since lower levels of evidence are inadequate. We have argued that reproductive medicine requires special considerations because, like clinical oncology, fertility treatments (especially in older women) are time dependent. Unlike clinical oncology, reproductive medicine, however, does not receive substantial financial research support from government or industry and, at least in the United States, has, therefore, to be primarily funded via patient revenues. Given a 50% chance of receiving placebo, infertility patients are, understandably, reluctant to fund their own RCTs. We here selectively review this subject, contrasting opposing opinions recently published in the literature by a prominent reproductive scientist and one of the world's leading experts on evidence-based medicine. Placing these recent publications into the evolving context of infertility practice, as also addressed in this journal in recent publications, we conclude that objective reasons explain why relatively few RCTs are performed in reproductive medicine and predict that this will not change in the foreseeable future. Reproductive medicine, therefore, has to find ways to develop satisfactory clinical evidence in other ways, satisfying patients' rights to easy access to potentially beneficial medical treatments with low costs and low risks. The RCTs should be reserved for relatively high risk and/or high cost treatments.