Funding for this research was provided by:
Ministeriet Sundhed Forebyggelse (903516)
Strategiske Forskningsråd (0603-00280B)
Received: 6 July 2020
Accepted: 17 July 2020
First Online: 7 August 2020
Ethics approval and consent to participate
: This study followed the principles of the Declaration of Helsinki, and was approved by the Ethics Committee for Copenhagen (The Danish National Committee on Health Research Ethics) (H-B-2008-093) and the Danish Data Protection Agency (2008-41-2599). Written informed consent was obtained from all participants.
: Written consent for publication has been obtained from the parents or legal guardians of all participants.
: The authors declare no conflict of interest.