1 Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55902. Electronic address: rose.carl@mayo.edu.
2 Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55902.
3 Department of Emergency Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55902.
4 Department of Anesthesiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55902.
5 Department of Obstetrics and Gynecology, Wake Forest University School of Medicine, Winston-Salem, NC 27157.