1. Childrens Nutritional Research Center, Childrens Hospital of Chongqing Medical University, Chongqing, P. R. China, and Department of Primary Child Care, Childrens Hospital of Chongqing Medical University, Chongqing, P. R. China
2. Childrens Nutritional Research Center, Childrens Hospital of Chongqing Medical University, Chongqing, P. R. China, and Department of Primary Child Care, Childrens Hospital of Chongqing Medical University, Chongqing, P. R. China, and Chengdu Maternal and Children Health Care Hospital, Chengdu, P.R. China
3. Childrens Nutritional Research Center, Childrens Hospital of Chongqing Medical University, Chongqing, P. R. China, and Pediatric research institute, Childrens Hospital of Chongqing Medical University, Chongqing, P. R. China