Clinical Research Department, London School of Hygiene and Tropical Medicine, London School of Hygiene & Tropical Medicine, Biomedical Research and Training Institute, Biomedical Research and Training Institute, MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, Biomedical Research and Training Institute, London School of Hygiene & Tropical Medicine, Biomedical Research and Training Institute, London School of Hygiene & Tropical Medicine - MRC Tropical Epidemiology Group (TEG), Department of Paediatrics, University of Zimbabwe, University of Southampton - Medical Research Council Life Course Epidemiology Unit, London School of Hygiene & Tropical Medicine - Department of Clinical Research and University of Bristol

MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, University of Bristol - Musculoskeletal Research Unit, University of Bristol, Parirenyatwa Group of Hospitals, Clinical Research Department, London School of Hygiene and Tropical Medicine, University of Sheffield - Academic Unit of Child Health, University of the Witwatersrand - School of Clinical Medicine, University of Southampton - Medical Research Council Life Course Epidemiology Unit, London School of Hygiene & Tropical Medicine - Department of Clinical Research, London School of Hygiene & Tropical Medicine and University of Southampton - Medical Research Council Life Course Epidemiology Unit