Funding for this research was provided by:
National Institute for Health Research (PHR-12/153/39)
Medical Research Council (RD1843)
United Kingdom Clinical Research Collaboration (MR/KO232331/1)
Received: 30 July 2018
Accepted: 9 June 2019
First Online: 28 June 2019
Ethics approval and consent to participate
: Ethical approval for this study was given by Wales 3 NHS Research Ethics Committee. Informed consent was received from parents of the children participating in this study by returning a stamped, addressed consent form to the study team.
: Not applicable.
: The authors declare that they have no competing interests.