1. The First Center of Maternal and Child Health Care Family Planning Service for the West Coast New Area of Qingdao, Department of Pediatrics, Qingdao, China;
2. The First Center of Maternal and Child Health Care Family Planning Service for the West Coast New Area of Qingdao, Department of Obstetrics, Qingdao, China;
3. The People's Hospital of the West Coast New Area of Qingdao, Department of Obstetrics, Qingdao, China;
4. The First Center of Maternal and Child Health Care Family Planning Service for the West Coast New Area of Qingdao, Department of Pediatrics of Traditional Chinese Medicine, Qingdao, China;
5. The Binhai Central Health Center of Huangdao, Department of Public Health, Qingdao, China