1International Peace Maternity and Child Health
Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai,
China
Correspondence: Rui-Hong Xue, MD
Postal address: No.910 Hengshan Road, Shanghai, China
Postal code: 200030. Work phone: +86-021-64070434
E-mail: wfmcxrh@alumni.sjtu.edu.cn
Disclosure of interests: The author declares no conflict of
interests.
Funding: None