[1] Univ Siena, Dept Pediat Obstet & Reprod Med, Policlin S Maria Scotte, I-53100 Siena, Italy
[2] Michael Johnson Fdn Hlth Res, Vancouver, BC, Canada
[3] Yale Univ, Dept Obstet Gynecol & Reprod Sci, Sch Med, New Haven, CT USA
[4] Univ Cincinnati, Dept Obstet & Gynecol, Coll Med, Cincinnati, OH USA
[5] Virginia Commonwealth Univ, Dept Obstet & Gynecol, Richmond, VA USA