1. Department of Obstetrics and Gynecology, Leiden University Medical Center, Leiden, The Netherlands
2. Department of Obstetrics and Gynecology, Haaglanden Medical Center, The Hague, The Netherlands
3. Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, The Netherlands
4. Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands