1. Division of Perinatal MedicineDepartment of PediatricsYale University School of MedicineNew HavenConnecticut06510USA
2. Department of MedicineDuke University Medical Center, and Veterans Affairs Medical CenterDurhamNorth Carolina27710USA
3. Departments of Biochemistry and Obstetrics and GynecologyThe Cecil H. and Ida Green Center for Reproductive Biology SciencesThe University of Texas Southwestern Medical CenterDallasTexas75235USA