1. Department of Clinical Science, Intervention and Technology; Karolinska Institutet; Stockholm Sweden
2. INSERM; Obstetrical, Perinatal and Paediatric Epidemiology Research Team; Centre for Epidemiology and Biostatistics (U1153); Paris-Descartes University; Paris France
3. Institute of Quality Assurance Hesse; Eschborn Germany
4. Department of Women's and Children's Health; Karolinska Institutet; Stockholm Sweden
5. Children's Hospital; Philipps University; Marburg Germany
6. Department of Neonatal Medicine; Karolinska University Hospital; Stockholm Sweden
7. Clinical Epidemiology Unit; Department of Medicine Solna; Karolinska Institutet; Stockholm Sweden