1. Unit of Public Health and Environmental Care, Department of Preventive Medicine, University of Valencia, Valencia, Spain
2. CIBER Epidemiology and Public Health (CIBERESP), Madrid, Spain
3. Research Unit for Gynaecology and Obstetrics, Institute of Clinical Research, University of Southern Denmark, Odense, Denmark
4. Department of Clinical Epidemiology, University of Aarhus, Aarhus, Denmark
5. Section for Epidemiology, Department of Public Health, University of Aarhus, Aarhus, Denmark