[1] Harvard Univ, Brigham & Womens Hosp, Sch Med, Dept Obstet & Gynecol, Boston, MA 02115 USA
[2] Harvard Univ, Sch Med, Harvard Pilgrim Hlth Care, Dept Ambulatory Care & Prevent, Boston, MA USA
[3] Harvard Univ, Sch Publ Hlth, Dept Nutr, Boston, MA 02115 USA
[4] Harvard Univ, Sch Publ Hlth, Dept Maternal & Child Hlth, Boston, MA 02115 USA
[5] Univ Rochester, Dept Pediat, Rochester, NY USA