Affiliation: | 1. Department of Reproductive Medicine, Yantai Yuhuangding Hospital, Affiliated Hospital of Medical College of Qingdao University, Yantai, Shandong, China,;2. Medical College of Shandong University, Jinan, Shandong, China, and;3. Department of Gynecology, Qingdao Women and Children Health Care Center, Qingdao, Shandong, China |