1. Gynecology Department, People’s Hospital of Wanning, Wanning, 571500 Hainan, China
2. Obstetrical Department, People’s Hospital of Wanning, Wanning, 571500 Hainan, China
3. Key Laboratory of Molecular Mechanism and Intervention Research for Plateau Diseases of Tibet Autonomous Region, School of Medicine, Xizang Minzu University, Xianyang, 712082 Shaanxi, China
4. Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, Xi’an, 710069 Shaanxi, China