1. Groene Hart Hospital; Department of Obstetrics and Gynaecology; PO box 1098 Gouda Netherlands 2800 BB
2. Leiden University Medical Center; Department of Obstetrics; PO Box 9600 Leiden Netherlands 2300 RC
3. Brighton and Sussex University Hospitals NHS Trust; Department of Obstetrics and Gynaecology; Royal Sussex County Hospital Eastern Road Brighton UK BN2 5BE
4. Academic Medical Centre; Obstetrics and Gynaecology; Meibergdreef 9 PO Box 22700 Amsterdam Netherlands 1105 AZ
5. 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