1. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Ohio State University, Columbus, Ohio, USA
2. Center for Biostatistics in AIDS Research, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA
3. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Brigham and Women’s Hospital/Harvard Medical School, Boston, Massachusetts, USA
4. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
5. Department of Epidemiology and Biostatistics, University of California at San Francisco, San Francisco, California, USA
6. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Duke University, Durham, North Carolina, USA