Measuring disadvantage in the early years in the UK: A systematic scoping review

•Measurement of disadvantage in child health is wide-ranging and multi-dimensional.•Social, economic, individual, and area-level are key concepts of disadvantage.•Area-level measures underestimate the association between disadvantage and child health.•Individual-level disadvantage indicators are needed in administrative data.•Policymakers planning child health interventions should measure disadvantage carefully.