1. Department of Obstetrics, Maternity and Child Health Hospital of Zhenjiang, Zhenjiang, Jiangsu 212001, P.R. China
2. Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, Jiangsu 210009, P.R. China
3. Central Laboratory of Medicine, Maternity and Child Health Hospital of Zhenjiang, Zhenjiang, Jiangsu 212001, P.R. China
4. Department of Obstetrics and Gynecology, The Affiliated People's Hospital of Jiangsu University, Zhenjiang, Jiangsu 212001, P.R. China
5. Department of Nursing, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China