1. Maternal and Child Health Research Program, Department of Obstetrics and Gynecology, Center for Research on Reproduction and Women’s Health Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
2. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Hospital of the University of Pennsylvania, 3400 Spruce Street, 585 Dulles Building, Philadelphia, PA 19104, USA