1. Academic Medical Centre, University of Amsterdam; Centre for Reproductive Medicine, Department of Obstetrics and Gynaecology; Center Meibergdreef 9 Amsterdam Netherlands 1105 AZ
2. Institute of Education, University of London; Evidence for Policy and Practice Information and Coordinating Centre (EPPI-Centre), Social Science Research Unit (SSRU); 10 Woburn Square London UK WC1H 0NR
3. The Royal College of Obstetricians & Gynaecologists; National Collaborating Centre for Women`s and Children`s Health; 27 Sussex Place, Regent´s Park London UK NW1 4RG
4. Auckland University; Cochrane MSDG FMHS; Grafton Campus Auckland New Zealand
5. University of Manchester; Health Methodology Research Group; R & D Support Unit, Salford Royal Hospital Stott Lane Salford UK M6 8HD
6. Academic Medical Center, University of Amsterdam; Center for Reproductive Medicine, Department of Obstetrics & Gynaecology; University of Amsterdam Meibergdreef 9 Amsterdam Netherlands 1105 AZ
7. Faculty of Medicine, Cairo University; Obstetrics & Gynaecology; 8 Moustapha Hassanin St Manial Cairo Egypt