1 Department of Obstetrics and Gynecology, Harbor-UCLA Medical Center, 1000 West Carson Street, Box 467, Torrance, CA 90502. Electronic address: mikeross@ucla.edu.
2 Departments of Obstetrics and Gynecology and Physiology, University of Western Ontario, St Joseph's Health Centre, London, Canada.
3 CHU Ste-Justine Research Center, Department of Obstetrics and Gynaecology, Université de Montréal, Montréal, QC, Canada.