1 Cardiovascular & Metabolic Diseases, Quintiles, Inc., 5927 S. Miami Boulevard, Morrisville, NC 27560, USA ; Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, NC 27710, USA.
2 Department of Obstetrics and Gynecology, McMaster University, Hamilton, ON, Canada L8S 4K1.
3 Department of Obstetrics and Gynecology, University of California, San Diego, San Diego, CA 92037-1300, USA.
4 Department of Gynecology and Obstetrics, University Medical Center Schleswig-Holstein, Campus Kiel, Arnold-Heller-Straße 3, House 24, 24105 Kiel, Germany.