1. Shandong University, Jinan, Shandong Province 250002, China
2. Department of Reproductive Medicine, The Affiliated Yantai Yuhuangding Hospital ofQingdao University, Yantai, Shandong Province 264000, China
3. Weifang Medical University, Weifang, Shandong Province 261021, China
4. Department of Obstetrics and Gynecology, Rizhao Hospital of Traditional Chinese Medicine, Rizhao, Shandong Province 276800, China
5. Department of Reproductive Medicine, The Affiliated Weihai Hospital of Qingdao University, Weihai, Yantai, Shandong Province 264200, China