1. Department of Gynecology and Obstetrics, Onze Lieve Vrouwe Hospital, P.O. Box 95500, 1090 HM Amsterdam, The Netherlands
2. Institute of Health Policy and Management, Erasmus Medical Center, P.O. Box 1738, 3000 DR Rotterdam, The Netherlands
3. Department of Gynecology and Obstetrics, Academic Medical Center, University of Amsterdam, P.O. Box 22660, 1100 DD Amsterdam, The Netherlands
4. Department of Obstetrics and Gynecology and Division Obstetrics and Prenatal Medicine, Erasmus MC-Sophia, P.O. Box 2060, 3000 CB Rotterdam, The Netherlands