1. Department of Obstetrics and Gynecology, United Health Services Perinatal Center, 33-57 Harrison Street, Johnson City, NY 13790, USA
2. Department of Obstetrics and Gynecology, Baystate Medical Center, 759 Chestnut Street, Springfield, MA 01199, USA
3. Department of Obstetrics and Gynecology, University of Florida College of Medicine, 653-1 W. 8th Street, Jacksonville, FL 32209, USA