1. Division of Women's and Perinatal Pathology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
2. Department of Obstetrics and Gynecology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
3. Department of Pathology, Children's Hospital Boston and Harvard Medical School, Boston, MA, USA
4. Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA, and Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA
5. Department of Pathology, University of California San Diego, La Jolla, CA, USA