1. Department of Gynecology, The Affiliated Hangzhou Hospital of Nanjing Medical University, Hangzhou, Zhejiang 310008, P.R. China
2. Department of Reproductive Medicine, Shanghai Tenth People's Hospital, Affiliated to Tongji University, Shanghai 200003, P.R. China
3. Department of Pathology, Hangzhou Women's Hospital, Hangzhou, Zhejiang 310008, P.R. China
4. Department of Ultrasound, Shanghai First Maternity and Infant Hospital, Shanghai 200000, P.R. China
5. Department of Reproductive Medicine, Hangzhou Women's Hospital, Hangzhou, Zhejiang 310008, P.R. China