1. Department of Pediatrics, Shunde Women and Children's Hospital of Guangdong Medical University, Foshan, China;
2. Department of Pediatrics, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China;
3. Department of Pediatrics, The Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, China;
4. Foshan Fosun Chancheng Hospital, Foshan, China; and
5. Key Laboratory of Research in Maternal and Child Medicine and Birth Defects, Guangdong Medical University, Foshan, China