[1] Eastern Virginia Med Sch, CONRAD, Dept Obstet & Gynecol, Arlington, VA 22209 USA
[2] Family Hlth Int, Res Triangle Pk, NC 27709 USA
[3] Univ Pittsburgh, Dept Obstet Gynecol & Reprod Sci, Pittsburgh, PA 15213 USA
[4] Magee Womens Res Inst, Pittsburgh, PA 15213 USA
[5] Profamilia, Santo Domingo 10401, Dominican Rep
[6] Eastern Virginia Med Sch, CONRAD, Dept Obstet & Gynecol, Norfolk, VA 23507 USA
[7] Brigham & Womens Hosp, Dept Obstet Gynecol & Reprod Biol, Boston, MA 02120 USA
[8] Harvard Univ, Sch Med, Boston, MA 02120 USA