1. The University of Cologne Women's Hospital, Köln, Germany; Department of Obstetrics and Gynecology, The University of Chicago Lying-in Hospital, Chicago, Illinois; Department of Obstetrics and Gynecology, University of Cologne, Kerpener Straße 34, D-50931 Köln, Germany
2. The University of Cologne Women's Hospital, Köln, Germany; Department of Obstetrics and Gynecology, The University of Chicago Lying-in Hospital, Chicago, Illinois