1. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, South Carolina
2. Department of Obstetrics and Gynecology, University of Texas Health Science Center at Houston, Houston, Texas
3. Center of Behavioral Epidemiology and Community Health (CBEACH), San Diego State University, San Diego, California
4. Department of Obstetrics and Gynecology, Central Baptist Hospital, Lexington, Kentucky
5. Mednax/Obstetrix Medical Group, Campbell, California
6. Department of Obstetrics and Gynecology, Saint Peter's University Hospital, New Brunswick, New Jersey
7. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of North Carolina, Chapel Hill, North Carolina
8. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Columbia University Medical Center, New York
9. Department of Obstetrics and Gynaecology, St Geroge's, University of London, London, United Kingdom
10. Department of Reproductive Medicine, University of California San Diego, La Jolla, California