[1] Washington Univ, Sch Med, Dept Obstet & Gynecol, St Louis, MO 63110 USA
[2] Stanford Univ, Med Ctr, Dept Radiat Oncol, Div Radiat & Canc Biol, Stanford, CA 94305 USA
[3] Stanford Univ, Med Ctr, Dept Obstet & Gynecol, Stanford, CA 94305 USA
[4] Washington Univ, Dept Pathol & Immunol, Sch Med, St Louis, MO USA
[5] Washington Univ, Ctr Reprod Hlth Sci CRepHS, St Louis, MO 63130 USA