1. Department of Obstetrics and Gynecology, University of North Carolina School of Medicine, Chapel Hill, North Carolina
2. Georgetown University School of Medicine, Washington, District of Columbia
3. Department of Obstetrics and Gynecology, Maternal and Child Health Research Center, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
4. Department of Obstetrics and Gynecology, University of South Florida, Tampa, Florida
5. Department of Obstetrics and Gynecology, Duke University School of Medicine, Durham, North Carolina
6. Department of Obstetrics and Gynecology, University of California at Los Angeles, Los Angeles, California
7. Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, San Francisco, California
8. Department of Obstetrics and Gynecology, Brown University Warren Alpert Medical School, Providence, Rhode Island