1. Institute of Nutrition and Health, Qingdao University, Qingdao 266071, PR China
2. Department of Pediatric Cardiology, Nephrology and Rheumatism, The Affiliated Hospital of Qingdao University Medical College, Qingdao 266003, PR China
3. Department of Obstetrics, Affiliated Hospital of Qingdao University, Qingdao 266000, PR China
4. Department of Neonatology, The Affiliated Wuxi Maternity and Child Health Care Hospital of Nanjing Medical University, Wuxi 214002, PR China. E-mail: