1. School of Health Sciences, Catholic University of Central Africa, Yaoundé 1110, Cameroon
2. Department of Health Sciences, Public University of Navarra, 31008 Pamplona, Spain
3. Department of Nursing, Suldal Sykehjem, 4230 Sands, Norway
4. Department of Surgery, Medical and Social Sciences, University of Alcala de Henares, 28871 Alcalá de Henares, Spain
5. Department of Obstetrics and Gynecology, Institute of Clinical Sciences, University of Gothenburg, 413 46 Gothenburg, Sweden
6. Department of Obstetrics and Gynecology, Sahlgrenska University Hospital, 413 46 Gothenburg, Sweden
7. Department of Sociosanitary Sciences, University of Murcia, 30120 Murcia, Spain
8. Area of Epidemiology and Public Health, Healthcare Research Institute of Navarre (IdiSNA), 31008 Pamplona, Spain
9. CIBER in Epidemiology and Public Health (CIBERESP), Institute of Health Carlos III, 46980 Madrid, Spain
10. Department of Preventive Medicine, Clínica Universidad de Navarra, 31008 Pamplona, Spain