1. Unidad de Medicina Materno Fetal, Departamento de Obstetricia y Ginecología, Pontificia Universidad Catolica de Chile, Santiago, Chile,
2. Unidad de Medicina Materno Fetal, Departamento de Obstetricia y Ginecología, Pontificia Universidad Catolica de Chile, Santiago, Chile
3. Department of Obstetrics and Gynecology, Faculty of Medicine, Pontificia Universidad Catolica de Chile, Santiago, Chile
4. Department of Obstetrics and Gynecology, University of Kansas School of Medicine, Kansas City, Kansas