1. Division of Maternal–Fetal Medicine, Department of Obstetrics and Gynecology, Eastern Virginia Medical School Norfolk VA USA
2. Sidney Kimmel Medical College Thomas Jefferson University Philadelphia PA USA
3. Division of Maternal–Fetal Medicine, Department of Obstetrics and Gynecology Sidney Kimmel Medical College, Thomas Jefferson University Philadelphia PA USA
4. Department of Pathology Beth Israel Deaconess Medical Center, Harvard Medical School Boston MA USA