1. Centre for Biostatistics, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
2. Department of Reproductive Medicine, Manchester Academic Health Science Centre, Manchester University NHS Foundation Trust, Manchester, UK
3. Maternal and Fetal Health Research Centre, Faculty of Life Sciences, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK
4. Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK
5. Balliol College, University of Oxford, Oxford, UK
6. Cochrane Gynecology and Fertility Group, Department of Obstetrics and Gynaecology, University of Auckland, Auckland, New Zealand
7. Amsterdam UMC, University of Amsterdam, Center for Reproductive Medicine, Amsterdam Reproduction & Development Research Institute, Amsterdam, Netherlands