1 University of Texas Southwestern Medical Center in Dallas, Department of Obstetrics and Gynecology, 5939 Harry Hines Boulevard, Dallas, TX 75390, USA. Electronic address: denisse.holcomb@utsouthwestern.edu.
2 University of Texas Southwestern Medical Center in Dallas, Department of Obstetrics and Gynecology, 5323 Harry Hines Boulevard, Dallas, TX 75390-9032, USA. Electronic address: gary.cunningham@utsouthwestern.edu.