1. Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden;
2. Department of Pediatrics, Institute of Clinical Sciences, Umeå University, Umeå, Sweden;
3. Department of Pediatrics, Karolinska University Hospital, Huddinge, Stockholm, Sweden;
4. Department of Obstetrics and Gynecology, Lund University, Lund, Sweden;
5. Department of Pediatrics, Uppsala University Hospital, Uppsala, Sweden; and
6. Centre for Reproductive Epidemiology, Lund University, Lund, Sweden