1. Third Department of Obstetrics and Gynecology, University General Hospital “ATTIKON”, Medical School, National and Kapodistrian University of Athens, 124 62 Athens, Greece
2. First Department of Obstetrics and Gynecology, Alexandra Hospital, Medical School, National and Kapodistrian University of Athens, 115 28 Athens, Greece
3. Department of Obstetrics and Gynecology, Royal Cornwall Hospital, Treliske TR1 3LQ, UK
4. Cryogonia Cryopreservation Bank, 115 26 Athens, Greece