1 From the Departments of International Health and Population, Family, and Reproductive Health, Johns Hopkins Bloomberg School of Public Health, and the Department of Gynecology and Obstetrics, Johns Hopkins School of Medicine - both in Baltimore (A.A.C.); the Mother Infant Research Institute, Tufts Medical Center, and the Department of Obstetrics and Gynecology, Tufts University School of Medicine - both in Boston (P.M.C.); and the Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University School of Medicine, Palo Alto, CA (B.T.B.).