1. Department of Obstetrics and Gynecology Hospital Universitario de Torrejón, Torrejón de Ardoz Madrid Spain
2. School of Health Sciences Universidad Francisco de Vitoria, Pozuelo de Alarcón Madrid Spain
3. Department of Obstetrics and Gynecology Hospital Clínico San Cecilio, Instituto de Investigación Biosanitaria IBS Granada Spain
4. Department of Obstetrics and Gynecology Hospital Clínico Universitario ‘Virgen de la Arrixaca’, El Palmar Murcia Spain
5. Institute for Biomedical Research of Murcia, IMIB‐Arrixaca, El Palmar Murcia Spain
6. Department of Obstetrics and Gynecology Hospital Universitario ‘Virgen de las Nieves’ Granada Spain
7. Department of Obstetrics and Gynecology, University Hospital Brugmann Université Libre de Bruxelles Brussels Belgium
8. Hospiten Group Tenerife Canary Islands Spain
9. Obs/Gyn Dr Shterev Hospital Sofia Bulgaria
10. OSCAR Clinic Sofia Bulgaria
11. Fetal Medicine Unit, Department of Obstetrics and Gynecology BioCruces Health Research Institute, Hospital Universitario Cruces, Universidad del País Vasco (UPV/EHU), Barakaldo País Vasco Spain
12. CIBER Epidemiology and Public Health Clinical Biostatistics Unit, Hospital Ramón y Cajal Madrid Spain
13. Barts Research Centre for Women's Health, WHO Collaborating Centre Queen Mary University of London London UK