Funding for this research was provided by:
The Comprehensive Treatment of Very Low Birth Weight Infants (2017wsjs099)
Received: 15 December 2020
Accepted: 20 January 2021
First Online: 19 February 2021
: A signed written informed consent was obtained from each patient and the experimental procedures were all in accordance with the guideline of the Ethics Committee of Weifang People’s Hospital.
: Written informed consent for publication was obtained from each participant.
: The authors declare that they have no competing interests.