1. Department of Obstetrics and Gynecology, Shaoxing Maternity and Child Health Care Hospital, Shaoxing 312000, Zhejiang Province, China
2. School of Medicine, Shaoxing University, Shaoxing 312000, Zhejiang Province, China
3. Department of Medical Record, Shaoxing Maternity and Child Health Care Hospital, Shaoxing 312000, Zhejiang Province, China