Life course epidemiology is a research field and analytical approach examining the long-term influence of physical, social, behavioural, and biological exposures and experiences encountered across the entire lifespan, from gestation to old age, and potentially across generations, on health and disease patterns, susceptibility, and outcomes in adulthood and later life, as well as at the population level. It is characterized by its focus on the timing, duration, sequence, and accumulation of exposures, recognizing critical or sensitive periods in shaping health trajectories and population health dynamics.