1. Department of Obstetrics and Gynecology, The Third Xiangya Hospital of Central South University, 138 Tongzipo Rd, Changsha, 410013 Hunan, China
2. Department of Obstetrics and Gynecology, Hunan Provincial Maternal and Child Health Hospital, 53 Xiangchun Rd, Changsha, 410008 Hunan, China
3. Central South University, Xiangya School of Medicine, 172 Tongzipo Rd, Changsha, 410013 Hunan, China
4. Xiangya Medical Laboratory, Central South University, Changsha, Hunan 410078, China
5. The First Affiliated Hospital of Guangdong Pharmaceutical University, Guangzhou, China