1. School of Medicine, University of Glasgow, Glasgow G31 2ER, UK
2. Nuffield Department of Women’s and Reproductive Health, University of Oxford, Oxford OX3 9DU, UK
3. The Fertility Partnership, Oxford OX4 2HW, UK
4. Hill Dickinson, London SW1Y 6EE, UK
5. NIHR Bristol Biomedical Research Centre, Bristol BS8 2BN, UK