1. Department of Obstetrics, Northwest Women and Children’s Hospital, Xi’an, People’s Republic of China;
2. Department of Pathology, Northwest Women and Children’s Hospital, Xi’an, People’s Republic of China;
3. Department of Neonatology, Northwest Women and Children’s Hospital, Xi’an, People’s Republic of China;
4. Departments of Pediatrics and Neonatology, Children’s Hospital of Fudan University, Shanghai, China