1. From the Department of Obstetrics and Gynecology, Tufts Medical Center (A.L.Z.), the Departments of Radiology (A.P.), Pediatrics (D.H.E.), and Pathology (B.B.), Massachusetts General Hospital, and the Departments of Radiology (A.P.), Pediatrics (D.H.E.), and Pathology (B.B.), Harvard Medical School — all in Boston.