1. Department of Obstetrics and Gynecology; VU University Medical Center; Amsterdam The Netherlands
2. Department of Epidemiology and Biostatistics; VU University Medical Center; Amsterdam The Netherlands
3. Department of Medical Library; Vrije Universiteit Amsterdam; Amsterdam The Netherlands
4. Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Academic Medical Center; University of Amsterdam; Amsterdam, The Netherlands
5. Department of Obstetrics and Gynecology, The Robinson Institute, School of Medicine; University of Adelaide; Adelaide Australia
6. The South Australian Health and Medical Research Institute; Adelaide Australia
7. Department of Obstetrics and Gynecology, Academic Medical Center; University of Amsterdam; Amsterdam The Netherlands