1. Department of Obstetrics and Gynecology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong, China
2. Department of Obstetrics and Gynecology, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
3. The Second School of Clinical Medicine, Southern Medical University, Guangzhou, Guangdong, China
4. Foshan Women and Children Hospital Affiliated to Southern Medical University, Foshan, Guangdong, China
5. The First School of Clinical Medicine, Southern Medical University, Guangzhou, Guangdong, China
6. State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, Guangdong, China
7. Department of Obstetrics and Gynecology, The First People’s Hospital of Foshan, Foshan, Guangdong, China