1. Department of Obstetrics and Gynecology, Centro Hospitalar São João, Porto, Portugal
2. Faculty of Medicine, University of Porto, Porto, Portugal
3. Centro de Infertilidad y Reproduccion Humana, Barcelona, Spain
4. Department of Obstetrics and Gynecology, Clínica Universidad de Navarra, University of Navarra, Pamplona, Spain
5. Department of Obstetrics and Gynecology, University and Polytechnic Hospital La Fe, Valencia, Spain
6. Department of Obstetrics and Gynecology, University Hospital, Salamanca, Spain