[1] Karolinska Univ Hosp, Dept Pediat, Huddinge, Sweden
[2] Karolinska Inst, Dept Clin Invest Intervent & Technol, Stockholm, Sweden
[3] Uppsala Univ, Dept Womens & Childrens Hlth, Uppsala, Sweden
[4] Sahlgrens Univ Hosp, Dept Obstet & Gynecol, S-41345 Gothenburg, Sweden
[5] Umea Univ, Dept Clin Sci Obstetr & Gynecol, Umea, Sweden
[6] Linkoping Univ, Dept Obstet & Gynecol, Linkoping, Sweden
[7] Univ Orebro, Dept Pediat, Orebro, Sweden
[8] Lund Univ, Dept Hlth Sci, Lund, Sweden
[9] Uppsala Univ, Dept Obstet & Gynecol, Uppsala, Sweden
[10] Linkoping Univ, Dept Pediat, S-58183 Linkoping, Sweden
[11] Orebro Univ Hosp, Dept Obstet & Gynecol, Orebro, Sweden
[12] Karolinska Univ Hosp Solna, Dept Obstet & Gynecol, Stockholm, Sweden
[13] Uppsala Univ, Dept Pediat, Uppsala, Sweden
[14] Sahlgrens Univ Hosp, Dept Pediat, Gothenburg, Sweden
[15] Lund Univ, Dept Pediat, S-22100 Lund, Sweden
[16] Uppsala Univ, Dept Womens & Childrens Hlth, Uppsala, Sweden
[17] Karolinska Univ Hosp, Dept Pediat, Huddinge, Sweden
[18] Karolinska Univ Hosp Huddinge, Dept Obstet & Gynecol, Stockholm, Sweden
[19] Uppsala Univ, Dept Ophthalmol, Uppsala, Sweden
[20] Nordland Hosp, Dept Pathol, Bodo, Norway
[21] Lund Univ, Dept Psychol, S-22100 Lund, Sweden
[22] Lund Univ, Ctr Reprod Epidemiol, S-22100 Lund, Sweden
[23] Karolinska Inst, Dept Women & Child Hlth, Stockholm, Sweden
[24] Astrid Lindgren Childrens Hosp, Stockholm, Sweden
[25] Lund Univ, Dept Obstet & Gynecol, S-22100 Lund, Sweden
[26] Umea Univ, Dept Clin Sci, S-90187 Umea, Sweden
[27] Sahlgrens Univ Hosp, Dept Obstet & Gynecol, Gothenburg, Sweden
[28] Lund Univ, Dept Med Eth, S-22100 Lund, Sweden
[29] Natl Board Hlth & Welf, Ctr Epidemiol, Stockholm, Sweden