1. Department of Gynecology, Qingdao Municipal Hospital, Qingdao, Shandong, China
2. Department of Gynaecology, JingZhou Hospital of Traditional Chinese Medicine, Jingzhou, Hubei, China
3. Department of Pediatric General Internal Medicine, Gansu Provincial Maternity and Child-care Hospital, Lanzhou, Gansu, China
4. Department of Gynecology, Maternal and Child Health Hospital of Hubei Province, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China