1. Department of Obstetrics and Gynecology, Columbia University Medical Center, New York, NY, USA
2. Clinical Research Center, Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk, VA, USA
3. Department of Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco and East Bay Physicians Medical Group, Sutter East Bay Medical Foundation, Berkeley, CA, USA
4. Department of Obstetrics and Gynecology, University of Virginia Health System, Charlottesville, VA, USA
5. Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine, New Haven, CT, USA