[1] Austin Maternal Fetal Med, St Davids Womens Ctr Texas, Austin, TX 78758 USA
[2] Baylor Coll Med, Dept Obstet & Gynecol, Houston, TX 77030 USA
[3] George Washington Univ, US Dept HHS, Natl Healthcare Preparedness Program, Washington, DC USA
[4] George Washington Univ, Dept Emergency Med, Washington, DC USA