1 Department of Obstetrics and Gynecology, Vanderbilt University Medical Center, 1161 21 Ave. S., R1217 Medical Center North, Nashville, TN 37232-2521. Electronic address: Ronald.alvarez@vumc.org.
2 Department of Obstetrics and Gynecology, Medical University of South Carolina, Charleston, SC.
3 Department of Obstetrics and Gynecology, The University of New Mexico, Albuquerque, NM.