1. Department of Gynaecology and Obstetrics, The Second Hospital, Jilin University, Changchun, Jilin 130021, P.R. China
2. Department of Rehabilitation, School of Nursing, Jilin University, Changchun, Jilin 130022, P.R. China
3. Department of Reproductive Endocrinology, Women's Hospital, Zhejiang University, School of Medicine, Hangzhou, Zhejiang 310006, P.R. China