Affiliation: | 1. Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, USA;2. Childbirth Research Associates, LLC, North Hollywood, California, USA;3. Department of Obstetrics and Gynecology, Division of Maternal Fetal-Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA;4. Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, USA;5. Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, Loma Linda University, Loma Linda, California, USA |