[1] Thomas Jefferson Univ, Sidney Kimmel Med Coll, Dept Obstet & Gynecol, Div Maternal Fetal Med, 833 Chestnut St,First Floor, Philadelphia, PA 19107 USA
[2] Geisinger, Dept Obstet & Gynecol, Div Maternal Fetal Med, Danville, PA USA
[3] Rutgers Robert Wood Johnson Med Sch, Dept Obstet & Gynecol, Div Maternal Fetal Med, New Brunswick, NJ USA
[4] Multicare Hlth Syst, Dept Obstet & Gynecol, Div Maternal Fetal Med, Tacoma, WA USA