1. Department of Obstetrics, Jining No. 1 People's Hospital, Jining, Shandong 272011, P.R. China
2. Department of Pharmacy, Yidu Central Hospital of Weifang, Weifang, Shandong 262500, P.R. China
3. Department of Respiratory Medicine, The People's Hospital of Zhangqiu Area, Jinan, Shandong 250200, P.R. China
4. Department of Obstetric Delivery Room, The People's Hospital of Zhangqiu Area, Jinan, Shandong 250200, P.R. China
5. Department of Rehabilitation, The People's Hospital of Zhangqiu Area, Jinan, Shandong 250200, P.R. China
6. Ward 1, Department of Gynecology, Jining No. 1 People's Hospital, Jining, Shandong 272011, P.R. China