Affiliation: | 1. Department of Obstetrics and Gynecology, The Affiliated Obstetrics and Gynecology Hospital of Nanjing Medical University, Nanjing Maternity and Child Health Care Hospital, Nanjing, China;2. Nantong Maternity and Child Health Care Hospital, Nantong, China;3. Nanjing Medical University, Nanjing, China |