[1] Dept Publ Hlth & Clin Med, Umea, Sweden
[2] Dept Internal Med & Clin Nutr, Gothenburg, Sweden
[3] Dept Womens & Childrens Hlth, Stockholm, Sweden
[4] Fac Med, Lund, Sweden
[5] Inst Med, Gothenburg, Sweden
[6] Dept Woman & Child Hlth, Uppsala, Sweden
[7] Swedish Natl Airway Register, Gothenburg, Sweden
[8] Acad Primary Hlth Care Ctr, Stockholm, Sweden
[9] Dept Resp Med & Allergol, Lund, Sweden
[10] Dept Hlth, Lulea, Sweden