1. Generation R Study Group, Erasmus MC, University Medical Center, PO Box 2040, 3000 CA Rotterdam, The Netherlands
2. Department of Pediatrics, Erasmus MC, University Medical Center, PO Box 22040, 3000 CA Rotterdam, The Netherlands
3. Department of Pediatrics, Leiden University Medical Center, Postbus 9600, 2300 RC Leiden, The Netherlands
4. Department of Radiology and Nuclear Medicine, Erasmus MC, University Medical Center, PO Box 22040, 3000 CA Rotterdam, The Netherlands