1. Maternité Hôpitaux Universitaires de Genève; Département de Gynécologie et d'Obstétrique, Unité de Développement en Obstétrique; Boulevard de la Cluse, 32 Genève 14 Switzerland CH-1211
2. The University of Liverpool; Cochrane Pregnancy and Childbirth Group, Department of Women's and Children's Health; First Floor, Liverpool Women's NHS Foundation Trust Crown Street Liverpool UK L8 7SS
3. University of Nottingham; Division of Child Health, Obstetrics and Gynaecology, School of Medicine; Nottingham City Hospital NHS Trust Hucknall Road Nottingham Nottinghamshire UK NG5 1PB