The European Society of Human Reproduction and Embryology published Bologna criteria to generate a definition of poor ovarian responders IPORsI. However, there are few data on whether PORs are homogenous for ovarian response or live birth rates ILBRsI. In this retrospective study, 821 patients fulfilling Bologna criteria and undergoing intracytoplasmic sperm injection were stratified into four groups: Group A: female age >= 40 with a previous poor response [cycle cancelled or oocytesl (105 patients, 123 cycles); Group B: female age >= 40 with an antral follicle count IAFCI < 7 (159 patients, 253 cycles); Group C: AFC <7 with a previous poor response 1350 patients, 575 cyclesl); and Group D: female age >= 40 with an AFC <7 and previous poor response (207 patients, 30b cycles). Cluster data analysis was performed. Although median number of oocytes was higher in Group B (P< 0.001), higher implantation (P = 0.024) and LBR per embryo transfer (P < 0.001) or cycle (P = 0.001) were noted in Group C. We conclude that, once a patient fulfils Bologna criteria, prognosis is poor, with fewer than 10% recorded LBRs per cycle. However, the LBRs are not homogenous and 'young proven' PORs have the most favourable pregnancy outcome. (C) 2017 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.