[1] University Medical Centre Utrecht/Wilhelmina Children's Hospital,
[2] Utrecht,undefined
[3] The Netherlands Fax: +31-30-2505325,undefined
[4] Department of Pediatrics,undefined
[5] Leiden University Medical Center,undefined
[6] Leiden,undefined
[7] The Netherlands,undefined
[8] Faculty of Medicine,undefined
[9] University of Utrecht,undefined
[10] Utrecht,undefined
[11] The Netherlands,undefined
[12] Health Department,undefined
[13] GG&GD,undefined
[14] Regio IJssel Vecht,undefined
[15] Zwolle,undefined
[16] The Netherlands,undefined
[17] Centre for Biostatistics,undefined
[18] University of Utrecht,undefined
[19] Utrecht,undefined
[20] The Netherlands,undefined
[21] Department of Methodology,undefined
[22] Faculty of Psychology,undefined
[23] University of Amsterdam,undefined
[24] Amsterdam,undefined
[25] The Netherlands,undefined