[1] Univ Hosp KU Leuven, Div Woman & Child, Louvain, Belgium
[2] Childrens Hosp Philadelphia, Ctr Fetal Diag & Treatment, Philadelphia, PA 19104 USA
[3] Hosp Clin Barcelona, Dept Obstet, Barcelona, Spain
[4] Hop Necker Enfants Malad, Dept Obstet, Paris, France
[5] Univ Med Ctr Hamburg Eppendorf, Dept Obstet & Fetal Med, Hamburg, Germany
[6] Kings Coll Hosp London, Harris Birthright Ctr Fetal Med, London, England
[7] Brown Univ, Alpert Med Sch, Fetal Med Program, Providence, RI 02912 USA
[8] Univ Calif San Francisco, Fetal Treatment Ctr, San Francisco, CA 94143 USA