1. Health Economics Research Centre, Nuffield Department of Population Health, University of Oxford, Oxford, UK
2. Institute of Management, Scuola Superiore Sant’Anna, Pisa, Italy
3. National Perinatal Epidemiology Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK
4. Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences (NDORMS), University of Oxford, Oxford, UK