Affiliation: | 1. Department of Obstetrics and Gynecology, Boston Medical Center, Boston, Massachusetts, USA;2. Department of Obstetrics and Gynecology, Boston Medical Center, Boston, Massachusetts, USA Department of Obstetrics and Gynecology, Christus St. Vincent Hospital, Gallup, New Mexico, USA;3. Boston University School of Public Health, Boston, Massachusetts, USA Wake Forest School of Medicine, Winston-Salem, North Carolina, USA;4. Boston University School of Public Health, Boston, Massachusetts, USA |