1. Research Direction, Instituto Nacional de Perinatologia Isidro Espinosa de los Reyes, Mexico City, Mexico
2. Discipline of Obstetrics and Gynaecology, University of Adelaide, Adelaide, SA, Australia
3. Departments of Obstetrics and Gynecology, Pediatrics & Physiology, University of Alberta, Edmonton, Alberta, Canada
4. Escuela Nacional de Ciencias Biologicas, Instituto Politecnico Nacional, Mexico City, Mexico
5. Biochemistry Department, Faculty of Medicine, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico