Funding for this research was provided by:
National Research Foundation of Korea (No. 2014R1A5A2010008)
Received: 26 March 2020
Accepted: 13 May 2020
First Online: 26 June 2020
Ethics approval and consent to participate
: The present study was approved by the Keimyung University Dongsan Medical Center Institutional Review Board (approval No. 2014–09-007). Written informed consent was obtained from parents of all the infants.
: Not applicable.
: The authors have no conflicts of interest to disclose.