Correspondence:
Rui-hong Xue1,MD
1International Peace Maternity and Child Health
Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
Postal address: No.910 Hengshan Road, Shanghai, China
Postal code: 200030. Work phone: +86-021-64070434
E-mail: wfmcxrh@sjtu.edu.cn