1 Warren Alpert Medical School of Brown University, Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Women & Infants Hospital, Providence, Rhode Island.
2 University of Massachusetts Chan Medical School, Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Worcester, Massachusetts.
3 Warren Alpert Medical School of Brown University, Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Women & Infants Hospital; Department of Health Services, Policy and Practice, School of Public Health, Brown University, Providence, Rhode Island.