Diminished ovarian reserve, premature ovarian failure, poor ovarian responder-a plea for universal definitions

Diminished ovarian reserve (DOR) is characterized by poor fertility outcomes, and it represents a major challenge in reproductive medicine. Although consensus exists on the concept of DOR, its definition remains blurry. DOR has to be distinguished from premature ovarian failure (POF) and poor ovarian responders (POR), who are clearly defined. We performed a PubMed search with the terms "diminished ovarian reserve" and "in vitro fertilization (IVF)" to assess the homogeneity of the definition of DOR. Out of 121 articles, 14 gave a definition for DOR. Only one definition was used by two different teams (basal follicle-stimulating hormone (FSH) value > 10 IU/l) and eight teams used 11 different definitions. Among those, four definitions did not include antral follicular count (AFC) and seven studies did. Two definitions included the results from a previous cycle. The heterogeneity in the definition of DOR used in these studies contributes to confusing results. Hence, there is a need for a clear definition of DOR. It appears that AFC and anti-Mullerian hormone (AMH) serum levels are the most relevant criteria. One option could be the use of the following definition: (i) woman with any of the risk factors for POR and/or (ii) an abnormal ovarian reserve test (i.e., antral follicular count (AFC) < 5-7 follicles or AMH < 0.5-1.1 ng/ml). This hypothesis requires validation.