[1] Penn State Univ, Milton S Hershey Med Ctr, Penn State Coll Med, Dept Obstet Gynecol & Pathol,Div Maternal Fetal M, Hershey, PA 17033 USA
[2] Univ Rochester, Sch Med & Dent, Div Maternal Fetal Med, Rochester, NY USA
[3] Univ Rochester, Sch Med & Dent, Dept Pathol & Lab Med, Rochester, NY USA
[4] Univ Rochester, Sch Med & Dent, Dept Obstet & Gynecol, Rochester, NY 14642 USA
[5] Yale Univ, Sch Med, Dept Obstet Gynecol & Reprod Sci, New Haven, CT USA