[1] George Washington Univ, Sch Med & Hlth Sci, Dept Obstet & Gynecol, Washington, DC 20052 USA
[2] George Washington Univ, Sch Med & Hlth Sci, Dept Neurol, Washington, DC 20052 USA
[3] Vanderbilt Univ, Med Ctr, Dept Obstet & Gynecol, Div Maternal Fetal Med, Nashville, TN 37232 USA
[4] Ohio State Univ, Coll Med, Columbus, OH 43210 USA
[5] George Washington Univ, Sch Med & Hlth Sci, Dept Obstet & Gynecol, Div Maternal Fetal Med, Washington, DC 20052 USA