Nikolaos Polyzos is the Clinical and Scientific Director of the Department of Reproductive Medicine of Dexeus University Hospital in Barcelona, Spain, and a Professor of Reproductive Endocrinology in the Department of Clinical Medicine in the University of Aarhus, Denmark. He has served as a Medical Director in the Centre for Reproductive Medicine in Brussels until 2017 and as a Professor in Brussels until 2019. Professor Polyzos is the principal investigator in several large pioneering multinational trials and a key opinion leader in the field of Reproductive Medicine for the treatment of poor ovarian responders in IVF programs, prediction of ovarian response and premature ovarian ageing, with more than 150 invited lectures in international congresses. He is a Section Editor in reproductive Biomedecine Online, member of the ESHRE guideline development group for ovarian stimulation and has served as an Editorial Consultant for the PIER (Physician’s Information and Education Resource) of the American College of Physicians (ACP).