1. Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Qilu Hospital of Shandong University, Ji'nan, Shandong, China.
2. Department of Public Health, The Second Hospital of Shandong University, Ji'nan, Shandong, China.
3. Department of Urology, Qilu Hospital of Shandong University, Ji'nan, Shandong, China.
4. Department of Clinical Laboratory, Qilu Hospital of Shandong University, Ji'nan, Shandong, China.