1 Division of Hematology, Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada.
2 Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Duke University School of Medicine, Durham, North Carolina, USA; Division of Hematology, Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA; Department of Population Health Sciences, Duke University School of Medicine, Durham, North Carolina, USA. Electronic address: jjf7@duke.edu.