1 Neonatal Intensive Care Unit, Affiliated Women and Children's Hospital of Ningbo University, Ningbo, Zhejiang, China.
2 Department of Pediatric Surgery, Affiliated Women and Children's Hospital of Ningbo University, Ningbo, Zhejiang, China.
3 Department of Pediatric Surgery, Affiliated Women and Children's Hospital of Ningbo University, Ningbo, Zhejiang, China. Electronic address: nbwengang@163.com.