[1] Cent Baptist Hosp, Perinatal Diagnost Ctr, Lexington, KY USA
[2] Univ South, Dept Obstet & Gynecol, Div Maternal Fetal Med, Sewanee, TN 37375 USA
[3] Alere Womens & Childrens Hlth, Dept Clin Res, Atlanta, GA USA
[4] Univ Cincinnati, Sch Med, Dept Obstet & Gynecol, Cincinnati, OH USA