Delayed Embryo Transfer in Poor Responders

Inclusion Criteria: * Patient selection is based on the ESHRE consensus group 2011 definition of poor ovarian response (POR) (Bologna criteria): * At least two of the following three features must be present: 1. Advanced maternal age (≥40 years) or any other risk factor for POR; 2. A previous POR (≤3 oocytes with a conventional stimulation protocol); 3. An abnormal ovarian reserve test (i.e. Antral follicle count (AFC) \<5-7 follicles or Antimullerian hormone (AMH) \<0.5-1.1 ng/ml). Two episodes of POR after maximal stimulation are sufficient to define a patient as poor responder in the absence of advanced maternal age or abnormal Ovarian reserve test (ORT). By definition, the term POR refers to the ovarian response and, therefore, one stimulated cycle is considered essential for the diagnosis of POR. However, patients over 40 years of age with an abnormal ORT may be classified as poor responders since both advanced age and an abnormal ORT may indicate reduced ovarian reserve and act as a surrogate of ovarian stimulation cycle. In this case, the patients should be more properly defined as expected PORs. Exclusion Criteria: * Women with endometriosis, endocrinal problems, uterine abnormalities as well as male azospermia.