Funding for this research was provided by:
National Key Research and Development Program of China (2017YFA0104304)
National Natural Science Foundation of China (81571213)
National Natural Science Foundation of China (81800583, 81601539, 81601084)
Nanjing Medical Science and technique Development Foundation (QRX17006, QRX17057)
Nanjing Medical Science and Innovation Platform (ZDX16005)
Received: 22 January 2020
Revised: 22 April 2020
Accepted: 28 April 2020
First Online: 13 May 2020
Ethics approval and consent to participate
: All umbilical cord samples were taken after informed and written consent was obtained, and the study was approved by the Research Ethics Board of Nanjing Drum Tower Hospital (permit number: 2017–161-01).
: Not applicable.
: The authors declare that they have no competing interests.