1. The First Affiliated Hospital of Sun Yat‐sen University Guangzhou China
2. Eyast Branch of Provincial Hospital Affiliated to Shandong University Jinan China
3. The First Affiliated Hospital of Shandong First Medical University Jinan China
4. Shandong Provincial Maternal and Child Health Care Hospital Cheeloo College of Medicine Shandong University Jinan China
5. Qilu Hospital of Shandong University Jinan China
6. Jinan Maternity and Child Healthcare Hospital Jinan China
7. Yantai Yuhuangding Hospital Yantai China
8. W.F. Maternal and Child Health Hospital Weifang China
9. Linyi People's Hospital Linyi China
10. Linyi Maternal and Child Health Care Hospital Linyi China
11. Affiliated Hospital of Weifang Medical University Weifang China
12. Taian Central Hospital Taian China
13. Liaocheng People's Hospital Liaocheng China
14. Binzhou Medical University Hospital Binzhou China
15. Maternity and Child Health Care of Zaozhuang Zaozhuang China
16. Taian Maternal and Child Health Care Hospital Taian China
17. Dongying People's Hospital Dongying China
18. Affiliated Hospital of Jining Medical College Jining China
19. The Second Affiliated Hospital of Shandong First Medical University Jinan China
20. Jinan second Maternity and Child Health Care Hospital Jinan China
21. Tengzhou Central People's Hospital Tengzhou China
22. Zibo Maternal and Child Health Hospital Zibo China
23. Zibo Municipal Hospital Zibo China
24. Central Branch of Provincial Hospital Affiliated to Shandong University Jinan China
25. Juxian Peoples Hospital Rizhao China
26. Dezhou People's Hospital Dezhou China
27. Heze Municipal Hospital Heze China
28. Liaocheng Second People's Hospital Liaocheng China
29. Jinan Central Hospital Jinan China