1. Department of Obstetrics and Gynecology, Busan Paik Hospital, Inje University, College of Medicine, Busan, South Korea;
2. College of Medicine, Paik Institute for Clinical Research, Inje University, Busan, South Korea;
3. Department of Obstetrics and Gynecology, University of Virginia, Charlottesville, VA 22908, USA;
4. Department of Microbiology, Inje University, College of Medicine, Busan, South Korea