Hayley A Hutchings1
, Penney Upton2
, Wai-Yee Cheung1
, Alison Maddocks3
, Christine Eiser4
, John G Williams1
, Ian T Russell5
, Sonia Jackson6
and Meriel EM Jenney7 
1School of Medicine, Swansea University, Swansea, UK
2Institute of Health, Social Care and Psychology, University of Worcester, Worcester, UK
3National Public Health Services for Wales, Carmarthen, UK
4Child and Family Research Group, Department of Psychology, University of Sheffield, Sheffield, UK
5Institute for Medical and Social Care Research, University of Wales Bangor, Bangor, UK
6Thomas Coram Research Unit, Institute of Education, University of London, London, UK
7Department of Child Health, Cardiff and Vale NHS Trust, Cardiff, UK