Tracing the Genetic Footprints of the UK National Health Service

TL;DR

This study assesses the causal impact of the UK NHS's establishment in 1948 on early-life mortality and population genetics, revealing significant health improvements and shifts in genetic traits among cohorts born after its introduction.

Contribution

It provides the first causal evidence of NHS's effect on early-life mortality and demonstrates how large-scale health policies influence population genetic composition over time.

Findings

Significant decline in infant mortality and stillbirths after NHS introduction.

Cohorts born after NHS show higher PGIs linked to adverse traits and lower PGIs linked to positive traits.

Effects are strongest in disadvantaged areas and among males.

Abstract

The establishment of the UK National Health Service (NHS) in July 1948 was one of the most consequential health policy interventions of the twentieth century, providing universal and free access to medical care and substantially expanding maternal and infant health services. In this paper, we estimate the causal effect of the NHS introduction on early-life mortality and we test whether survival is selective. We adopt a regression discontinuity design under local randomization, comparing individuals born just before and just after July 1948. Leveraging newly digitized weekly death records, we document a significant decline in stillbirths and infant mortality following the introduction of the NHS, the latter driven primarily by reductions in deaths from congenital conditions and diarrhea. We then use polygenic indexes (PGIs), fixed at conception, to track changes in population composition, showing that cohorts born at or after the NHS introduction exhibit higher PGIs associated with contextually-adverse traits (e.g., depression, COPD, and preterm birth) and lower PGIs associated with contextually-valued traits (e.g., educational attainment, self-rated health, and pregnancy length), with effect sizes as large as 7.5% of a standard deviation. These results based on the UK Biobank data are robust to family-based designs and replicate in the English Longitudinal Study of Ageing and the UK Household Longitudinal Study. Effects are strongest in socioeconomically disadvantaged areas and among males. This novel evidence on the existence and magnitude of selective survival highlights how large-scale public policies can leave a persistent imprint on population composition and generate long-term survival biases.