Table 1 Definitions for each of the analysed Theoretical Lifecourse Models

Saturated

Combination of all the below models. Given three temporal SEP measures, this allows eight possible SEP trajectories. This is modelled using the main effects from each SEP life-stage, all two-way interactions and the three-way interaction.

1a) Accumulation

Longer-term exposure to lower SEP results in a proportionate increase in allostatic load.

  - Strict

Regardless of life-stage, the more occasions a respondent spends in a lower SEP environment the greater the effect on raising allostatic load. This is modelled by constraining the effect size between SEP and allostatic load to be equal across all three life-stages.

  - Relaxed

SEP at each time-point contributes to the risk of increasing allostatic load, but that these effects do not have to be equal (i.e. can have differing effect sizes in the association with allostatic load).

1b) Critical

Assumes that SEP at only a specific life-stage (childhood, the transition to adulthood or adulthood) will be associated with allostatic load, irrespective of other life-stages. These effects can be modelled by analysing each of the SEP measures of interest (childhood, the transition to adulthood or adulthood SEP) in turn, while constraining the other two life-stages to be zero.

1c) Mobility

Downward mobility has a negative impact on allostatic load (and the opposite effect for upward mobility).

  - Early

Mobility from childhood to the transitional period between childhood and adulthood (inter-generational mobility).

  - Adult

Mobility from the transitional period between childhood and adulthood, to adulthood (intra-generational mobility).*

No effect

Assumes that SEP has no association with allostatic load. Modelled by removing all SEP terms from the regression models.