1. Department of Clinical EpidemiologyAarhus University Hospital Aarhus Denmark
2. Department of Public Health, Section for EpidemiologyAarhus University Aarhus Denmark
3. NCRR‐The National Center for Register‐based Research, Department of Economics and Business Economics, Business and Social ScienceAarhus University Aarhus Denmark
4. Department of EpidemiologyUniversity of California Los Angeles California
5. Information Services DepartmentTHL National Institute for Health and Welfare Helsinki Finland
6. Department of Neurobiology, Care Sciences and Society, Division of Family MedicineKarolinska Institute Stockholm Sweden
7. Research Centre for Child PsychiatryUniversity of Turku Turku Finland