1. Department of Obstetrics & Gynecology, University of Tennessee Health Science Center, Memphis, TN, USA;
2. Department of Obstetrics & Gynecology, University of South Florida, Tampa, FL, USA;
3. Department of Preventive Medicine, University of Tennessee Health Science Center, Memphis, TN, USA;
4. Sanford Medical Center, Department of Obstetrics & Gynecology. Bismarck, ND, USA