[1] Univ Hosp Schleswig Holstein, Dept Gynecol & Obstet, Div Prenatal Med, D-23538 Lubeck, Germany
[2] Caritas Hosp St Josef, Dept Obstet & Gynecol, Regensburg, Germany
[3] Univ Giessen, Div Prenatal Med, Dept Obstet & Gynecol, Giessen, Germany
[4] Univ Bonn, Dept Obstet & Prenatal Med, D-5300 Bonn, Germany