1 Medical Research Council Lifecourse Epidemiology Unit, University of Southampton, Southampton SO16 6YD, United Kingdom.
2 Paediatric Endocrinology, University Hospitals Southampton National Health Service Foundation Trust, Southampton SO16 6YD, United Kingdom.
3 National Institute for Health Research Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton National Health Service Foundation Trust, Southampton SO16 6YD, United Kingdom.
4 National Institute for Health Research Musculoskeletal Biomedical Research Unit, University of Oxford, Oxford OX3 7LD, United Kingdom.