[1] Brigham & Womens Hosp, Dept Obstet & Gynecol, 75 Francis St, Boston, MA 02115 USA
[2] Harvard Med Sch, Massachusetts Gen Hosp, Dept Obstet & Gynecol, Boston, MA USA
[3] Harvard Med Sch, Brigham & Womens Hosp, Dana Farber Canc Inst,Div Gynecol Oncol,Dept Obst, New England Trophoblast Dis Ctr,Trophoblast Tumor, Boston, MA USA