[1] Vanderbilt Univ, Med Ctr, Dept Obstet & Gynecol, Div Maternal Fetal Med, Nashville, TN 37232 USA
[2] Vanderbilt Univ, Med Ctr, Dept Pediat, Div Neonatal Perinatal Med, Nashville, TN USA
[3] Vanderbilt Univ, Med Ctr, Dept Med, Div Infect Dis, Nashville, TN USA
[4] Vanderbilt Univ, Med Ctr, Dept Pathol Microbiol & Immunol, Nashville, TN USA
[5] Vanderbilt Univ, Med Ctr, Dept Obstet & Gynecol, Nashville, TN USA