1. Department of Obstetrics and Gynecology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, People’s Republic of China
2. Maternal and Child Health Hospital of Zigong, Sichuan, People’s Republic of China
3. Department of Obstetrics and Gynecology, Hubei Maternity and Child Health Care Hospital, Wuhan, Hubei, People’s Republic of China
4. The Central Hospital of Enshi Autonomous Prefecture, Enshi Autonomous Prefecture, Hubei, People’s Republic of China