Funding for this research was provided by:
National Center for Chronic Disease Prevention and Health Promotion (26-26)
Received: 11 June 2020
Accepted: 26 January 2021
First Online: 22 February 2021
Ethics approval and consent to participate
: This study was approved by the Ethics Committees of the National Center for Child Health and Development in December 2014 (No. 74) and of the Japan Pediatric Society in March 2015. Written informed consent was obtained from the participants.
: Not applicable.
: The Authors declare that there is no conflict of interest.