1. Department of Pediatrics, Women's and Children's Hospital, Chongqing Medical University, Chongqing, P.R. China.
2. Department of Pediatrics, Children's Hospital, Chongqing Medical University, Chongqing, P.R. China.
3. Department of Gynecology and Obstetrics, Chongqing Health Center for Women and Children, Chongqing, P.R China.
4. Department of Pediatric General Surgery, Chongqing University Three Gorges Hospital, Chongqing, P.R. China.
5. Department of Pediatric General Surgery, Chongqing Maternal and Child Health Hospital, Chongqing Medical University, Chongqing, P.R China.