1. Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
2. Department of Orthopedics and Sports Medicine, University of Washington School of Medicine, Seattle, Washington
3. Department of Obstetrics and Gynecology, John H. Stroger, Jr. Hospital of Cook County, Cook County Health, Chicago, Illinois
4. Section of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Pritzker School of Medicine, The University of Chicago, Chicago, Illinois