Funding for this research was provided by:
Beijing Obstetrics and Gynecology Hospital, Capital Medical University (FCYY201624)
Received: 7 August 2019
Accepted: 2 March 2020
First Online: 6 March 2020
Ethics approval and consent to participate
: This study was approved by the Ethics Committee of Beijing Obstetrics and Gynecology Hospital and was in accordance with the 1964 Helsinki Declaration and its later amendments. Each participant in this study signed an informed consent form to participate in this study.
: Each participant in this study signed an informed consent form for publication of all of the participants’ clinical details.
: The authors declare that they have no competing interests.