1. Department of Obstetrics, Jining No.�1 People's Hospital, Jining, Shandong�272011, P.R. China
2. Department of Obstetrics, People's Hospital of Zhangqiu District, Jinan, Shandong�250200, P.R. China
3. Department of Oral and Maxillofacial Surgery, People's Hospital of Zhangqiu District, Jinan, Shandong�250200, P.R. China
4. Department of Otorhinolaryngology, People's Hospital of Zhangqiu District, Jinan, Shandong�250200, P.R. China
5. Department of Endocrinology, People's Hospital of Zhangqiu District, Jinan, Shandong�250200, P.R. China
6. Department of Anesthesiology, Jining No.�1 People's Hospital, Jining, Shandong�272011, P.R. China