1. Department of Obstetrics and Gynecology, Warren Alpert Medical School at Brown University, Providence, Rhode Island, USA.
2. Department of Medicine, Washington University in St. Louis, St. Louis, Missouri, USA.
3. Department of Emergency Medicine, Warren Alpert Medical School at Brown University, Providence, Rhode Island, USA.
4. Department of Women's Health, Dell Medical School, University of Texas at Austin, Austin, Texas, USA.
5. Department of Epidemiology, Brown School of Public Health, Providence, Rhode Island, USA.