1. Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas
2. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Baylor College of Medicine, Houston, Texas
3. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Wisconsin-Madison, Madison, Wisconsin
4. Department of Immunology and Pathology, Baylor College of Medicine, Houston, Texas
5. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Texas Health Science Center at Houston, Houston, Texas