Against the grain: International migrants, the children of migrants and national life expectancy in Sweden, 1990-2019.

International migrants and their children represent increasing shares of the populations of major host countries and have growing potential to affect estimates of national mortality. Yet, while many studies have observed mortality differences between migrants, their children, and the majority population, few have progressed beyond this point to quantify the actual impact of these differences upon national life expectancy levels. Studies that have, reveal that migrants increasingly enhance national life expectancy, but do not progress beyond a single average generational effect. Here, using established demographic methods, we aim to quantify and unpack the impact of migrants and the children of migrants on national life expectancy in Sweden, with emphasis on potential differences by age, generations, and migration background. Going "against the grain" relative to other countries, we reveal an initial negative effect of first-generation migrants on national life expectancy levels in Sweden, followed by a gradual waning and disappearance of this effect over time. This change is attributable to the transformation in origin composition of Sweden's migrant population from migrants born in Nordic countries (that have higher mortality than the majority population) to migrants born in non-Western countries (that have lower mortality than the majority population), particularly at working ages. For children of migrants, nearly all ages and migrant backgrounds contribute to an increasingly negative effect on national life expectancy over time. The unique and disparate mortality risks of migrants, the children of migrants, and the majority population suggest a need to monitor their mortality separately so as to maximise potential future gains in national life expectancy in Sweden.