[1] Univ Maryland, Dept Obstet Gynecol & Reprod Sci, Baltimore, MD 21201 USA
[2] Univ Hamburg, Dept Obstet & Prenatal Med, Hamburg, Germany
[3] Univ Padua, Dept Gynecol Sci & Human Reprod, I-35100 Padua, Italy
[4] Univ Amsterdam, Acad Med Ctr, Dept Obstet & Gynecol, NL-1105 AZ Amsterdam, Netherlands
[5] Univ Bonn, Dept Obstet & Prenatal Med, D-5300 Bonn, Germany
[6] Univ Milan, Dept Obstet & Gynecol, I-20122 Milan, Italy
[7] Univ Schleswig Holstein, Dept Gynecol & Obstet, Lubeck, Germany
[8] Kings Coll Hosp London, Harris Birthright Res Ctr Fetal Med, London, England
[9] Univ Fauenklin Charite, Dept Prenatal Diag & Therapy, Berlin, Germany
[10] Univ London St Georges Hosp, Sch Med, Fetal Med Unit, London SW17 0RE, England
[11] Hanau City Hosp, Dept Obstet & Gynecol, Henau, Germany
[12] Univ Colorado, Hlth Sci Ctr, Dept Obstet & Gynecol, Boulder, CO 80309 USA