Wu, Jiang-Nan
Gu, Wei-Rong
Xiao, Xi-Rong
Zhang, Yi
Li, Xiao-Tian
Yin, Chuan-Min
Article History
Received: 20 October 2017
Revised: 29 May 2018
Accepted: 9 October 2018
First Online: 30 October 2018
Compliance with ethical standards
:
: The study was approved by the Ethics Committee of the Obstetrics and Gynecology Hospital of Fudan University (NO. 30-2015). Consent to participate was not obtained because this study employed a retrospective cohort design.
: The authors declare that they have no conflict of interest.