[1] Karolinska Inst, Dept Woman & Child Hlth, S-10401 Stockholm, Sweden
[2] Umea Univ, Dept Pathol, S-90187 Umea, Sweden
[3] Haukeland Hosp, Dept Paediat, N-5021 Bergen, Norway
[4] Glostrup Univ Hosp, Dept Paediat, Glostrup, Denmark
[5] Rigshosp, Dept Paediat Surg, DK-2100 Copenhagen, Denmark
[6] St Olav Hosp, Sect Paediat Surg, Trondheim, Norway
[7] Rigshosp, Dept Growth & Reprod, DK-2100 Copenhagen, Denmark
[8] Karolinska Inst, Dept Anaesthesiol, S-10401 Stockholm, Sweden
[9] Akad Barnsjukhuset, Dept Paediat Surg, Uppsala, Sweden
[10] Univ Helsinki, Hosp Children & Adolescents, FIN-00014 Helsinki, Finland
[11] Landspital Univ Hosp, Childrens Hosp, Reykjavik, Iceland
[12] Univ Turku, Dept Paediat, SF-20500 Turku, Finland
[13] Univ Turku, Dept Physiol, SF-20500 Turku, Finland