[1] Brigham & Womens Hosp, Massachusetts Gen Hosp Integrated Residency, Program Obstet & Gynecol, Boston, MA 02115 USA
[2] Brigham & Womens Hosp, Dept Obstet & Gynecol, Div Maternal Fetal Med, Boston, MA 02115 USA
[3] Harvard Univ, Sch Med, Boston, MA 02115 USA
[4] Beth Israel Deaconess Med Ctr, Dept Obstet & Gynecol, Div Maternal Fetal Med, Boston, MA 02215 USA
[5] Univ Penn, Hosp, Dept Obstet & Gynecol, Div Maternal Fetal Med, Philadelphia, PA 19104 USA