1. Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology University of Colorado School of Medicine Aurora CO USA
2. Clinical Epidemiology and Public Health Research Unit Institute for Maternal and Child Health IRCCS Burlo Garofolo Trieste Italy
3. Unit of Fetal Medicine and Prenatal Diagnosis Institute for Maternal and Child Health IRCCS Burlo Garofolo Trieste Italy
4. Department of Medicine, Surgery and Health Sciences University of Trieste Trieste Italy
5. Department of Obstetrics and Gynecology Wayne State University Detroit MI USA
6. Colorado Fetal Care Center Children's Hospital of Colorado Aurora CO USA