1. Medical Department, The Maternal and Child Health Hospital of Jinan City, Shandong, China.
2. Department of Special Clinic, Changhai Hospital, Second Military Medical University, Shanghai, China.
3. Department of Surgery, The Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, China.
4. Department of Gynaecology, The Maternal and Child Health Hospital of Jinan City, Shandong, China.