1. Women’s Hospital, School of Medicine, Zhejiang University, Hangzhou, P. R. China,
2. Department of Obstetrics and Gynecology, The Second Hospital of Yinzhou, Ningbo, P. R. China,
3. Zhejiang Cancer Hospital, Hangzhou, P. R. China, and
4. The Second Hospital, School of Medicine, Zhejiang University, Hangzhou, P. R. China