1. Tommy’s National Centre for Miscarriage Research, Queen Charlottes and Chelsea Hospital, Imperial College, London, UK
2. Department of Obstetrics and Gynaecology, Imperial College Healthcare Trust, London, UK
3. Department of Obstetrics and Gynaecology, Chelsea and Westminster NHS Trust, London, UK
4. KU Leuven, ACHG, Department of Public Health and Primary Care, Kapucijnenvoer 33, Leuven, Belgium
5. Nuffield Department of Primary Care Health Sciences, University of Oxford, Woodstock Road, Oxford, UK
6. KU Leuven, Department of Obstetrics and Gynaecology, Herestraat, Leuven, Belgium