1. The Clinical Epidemiology Division Department of Medicine, Solna Karolinska Institutet Stockholm Sweden
2. Department of Women's Health Karolinska University Hospital Stockholm Sweden
3. Statens Serum Institut Copenhagen Denmark
4. Division of Infectious Diseases Department of Medicine, Solna Karolinska Institutet Stockholm Sweden
5. Department of Infectious Diseases Karolinska University Hospital Stockholm Sweden
6. The Public Health Agency of Sweden Solna Sweden
7. Department of Obstetrics and Gynecology Sahlgrenska University Hospital Gothenburg Sweden
8. Department of Obstetrics and Gynecology Sahlgrenska Academy University of Gothenburg Gothenburg Sweden
9. Department of Clinical Science, Intervention and Technology Karolinska Institutet Stockholm Sweden
10. Department of Neonatal Medicine Karolinska University Hospital Stockholm Sweden
11. Department of Medical Epidemiology and Biostatistics Karolinska Institutet Stockholm Sweden
12. Department of Paediatrics Örebro University Hospital Örebro Sweden