1. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, University of California, Los Angeles, Los Angeles, California, USA
2. University of Southern California, Keck School of Medicine, Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Los Angeles, California, USA
3. Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California, USA