[1] Univ Hosp Zurich, Dept Obstet, Ramistr 100, CH-8091 Zurich, Switzerland
[2] Univ Zurich, Fac Med, Ramistr 71, CH-8006 Zurich, Switzerland
[3] Univ Zurich, Zurich Ctr Fetal Diag & Therapy, CH-8006 Zurich, Switzerland
[4] Univ Childrens Hosp Zurich, Dept Pediat Surg, Steinwiesstr 75, CH-8032 Zurich, Switzerland
[5] Univ Childrens Hosp Zurich, Spina Bifida Ctr, Steinwiesstr 75, CH-8032 Zurich, Switzerland
[6] Univ Childrens Hosp Zurich, Childrens Res Ctr, Steinwiesstr 75, CH-8032 Zurich, Switzerland