1. Department of Pediatrics and Adolescent Medicine, Viborg Regional Hospital, Viborg, Denmark
2. Department of Pediatrics and Adolescent Medicine, Aarhus University Hospital, Aarhus, Denmark
3. Perinatal Epidemiology Research Unit, Aarhus University Hospital, Aarhus, Denmark
4. Department of Pediatrics and Adolescent Medicine, Randers Regional Hospital, Randers, Denmark
5. Section for Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark
6. Department of Epidemiology, Fielding School of Public Health, University of California, Los Angeles, Los Angeles, California, USA
7. Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark