1. Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
2. Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
3. Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, SC, USA
4. Department of Obstetrics and Gynecology, New York-Presbyterian Hospital/Queens, Queens, NY, USA
5. Department of Obstetrics and Gynecology, Brown University Alpert Medical School, Providence, RI, USA
6. Division of Maternal-Fetal Medicine, Department of Obstetrics-Gynecology, University of California School of Medicine, Irvine, CA, USA
7. Fountain Valley Regional Hospital and Medical Center, Fountain Valley, CA, USA