1. Department of Internal Medicine, Health Science Center, Ningbo University , Ningbo, Zhejiang, P. R. China
2. School of Public Health, Health Science Center, Ningbo University , Ningbo, Zhejiang, P. R. China
3. Zhejiang Key Laboratory of Pathophysiology, Health Science Center, Ningbo University , Ningbo, Zhejiang, P. R. China
4. Center for Reproductive Medicine, Ningbo Women and Children’s Hospital , Ningbo, Zhejiang, P. R. China
5. Department of Medical Records and Statistics, Affiliated People’s Hospital of Ningbo University , Ningbo, Zhejiang, P. R. China
6. Department of Medical Records and Statistics, Beilun People’s Hospital , Ningbo, Zhejiang, P. R. China
7. Department of Obstetrics and Gynecology, Yinzhou District Maternal and Child Health Care Institute , Ningbo, Zhejiang, P. R. China
8. Department of Obstetrics and Gynecology, Jiangbei District Maternal and Child Health Care Institute , Ningbo, Zhejiang, P. R. China
9. Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Health Science Center, Ningbo University , Ningbo, Zhejiang, P. R. China