Table 1

 Life-course models explaining the association between early-life circumstances and health in adulthood

Critical periodThis model implies that there is a period of development in early life during which exposures to deprivation have long-term effects on adult health, independent of adult circumstances28,29—for example, the fetal origins of disease hypothesis.30,31
PathwayThe early-life environment sets people on life trajectories or directions that in turn affect health status over time and into adulthood.32–34 The pathway model views early environment to be important, but only because it shapes and influences the socioeconomic trajectories of people.35 Circumstances in early life are seen as the initial stage in the pathway to adult health but with an indirect effect, influencing adult health through social trajectories such as restricting educational opportunities, thus influencing socioeconomic circumstances and health in later life.34
CumulativeThe intensity and duration of exposure to unfavourable or favourable physical and social environments throughout life affects health status in a dose–response fashion.36–40 Unfavourable circumstances throughout life are associated with the greatest risk of poor health in adulthood, whereas unfavourable circumstances at only one stage of life may be lessened by improved circumstances at another stage.34 This accumulation of risk approach emphasises both biological and social experiences in childhood, adolescence and early adulthood, and how these biological and social risk factors combine and form pathways between early-life experiences and adult disease.41