1. Department of Pediatrics; Faculty of Medicine and Health; Örebro University; Örebro Sweden
2. Department of Women's and Children's Health; Section for Pediatrics; Uppsala University; Uppsala Sweden
3. Department of Pediatrics; Institute of Clinical Sciences; Umeå University; Umeå Sweden
4. Department of Obstetrics and Gynecology, Clinical Sciences; Centre of Reproduction Epidemiology; University of Lund; Lund Sweden