1. Department of Obstetrics and Gynecology, Clínica Universidad de Navarra, School of Medicine, University of Navarra, Pamplona, Spain.
2. Department of Obstetrics and Gynecology, Complejo Hospitalario de Navarra, Pamplona, Spain.
3. Department of Obstetrics and Gynecology, General Hospital, Lanzarote, Spain.
4. Department of Obstetrics and Gynecology, Hospital La Inmaculada, Huércal-Overa, Spain.
5. Department of Obstetrics and Gynecology, University Hospital, Badajoz, Spain.
6. Department of Obstetrics and Gynecology, Azienda Ospedaliero Universitaria di Cagliari, Cagliari, Italy.