Recurrent miscarriage is a useful and valid clinical concept.

Although epidemiological, clinical and biochemical risk factors are known for recurrent miscarriage (RM), the etiology is mainly unknown. Two main hypotheses dominate: that RM is mainly caused by aneuploid conceptions and other conception errors and that the recurrence rate is explained by the combination of chance and increased risk, or that maternal endocrinological, thrombophilic or immunological abnormalities play a main role in causing loss of euploid conceptions. Believers of the former hypothesis advocate that management of RM should be conservative and that the spontaneous prognosis is very favorable. Believers of the latter hypothesis think that treatments aimed at the woman may improve pregnancy outcome, but that testing of such treatments in randomized controlled trials is needed. In this article in favor of RM being a specific and useful clinical concept, arguments are advanced that a significant subset of RM patients exhibit a poor spontaneous prognosis and should be offered relevant investigations, close surveillance during pregnancy, and treatment, preferably as part of randomized controlled trials.