1. Department of Public Health Research Unit for Epidemiology Aarhus University Aarhus Denmark
2. Department of Epidemiology Fielding School of Public Health University of California Los Angeles (UCLA) Los Angeles CA USA
3. Department of Public Health Research Unit for Biostatistics Aarhus University Aarhus Denmark
4. Department of Statistics UCLA College of Letters and Science Los Angeles CA USA
5. Department of Clinical Epidemiology Aarhus University Hospital Aarhus Denmark
6. Perinatal Epidemiology Research Unit Department of Paediatrics Aarhus University Hospital Aarhus Denmark