Affiliation: | 1. Department of Obstetrics and Gynecology, Amsterdam University Medical Centers, University of Amsterdam, Room H4-205, PO Box 22660, Amsterdam 1105 AZ, The Netherlands;2. Department of Obstetrics and Gynecology, University Medical Center Groningen, University of Groningen, Huispostcode CB20, Hanzeplein 1, Groningen 9700 RB, The Netherlands |