1. Department of Public Health Research Unit for Epidemiology Aarhus University Aarhus Denmark
2. Department of Obstetrics and Gynecology Aarhus University Hospital Aarhus Denmark
3. Department of Clinical Epidemiology Aarhus University Hospital Aarhus Denmark
4. Det Nationale Forskningscenter for Arbejdsmiljø Copenhagen Denmark
5. Department of Public Health University of Copenhagen Copenhagen Denmark
6. Department of Occupational and Environmental Medicine Bispebjerg and Frederiksberg University Hospital Frederiksberg Denmark