1. Department of Pediatrics, Huai’an Maternal and Child Health Care center (The Huai’an Maternity and Child Clinical College of Xuzhou Medical University), Huaian, Jiangsu, China
2. Department of Pediatrics, Xuyi People’s Hospital, Huaian, Jiangsu, China
3. Department of Ultrasonic, Huai’an NO.3 People’s Hospital, Huaian, Jiangsu, China.