1. International Peace Maternal and Child Health Hospital, Shanghai Jiaotong University, Shanghai, P. R. China
2. Department of Obstetrics and Gynecology, the 6th People's Hospital, Shanghai Jiaotong University, Shanghai, P. R. China
3. Laboratory for Reproductive Immunology, Hospital & Institute of Obstetrics and Gynecology, Fudan University Shanghai Medical College, Shanghai, P. R. China