Demographic winter: declining fertility and increasing life expectancy in South American countries

This study examines the demographic winter process in ten South American countries during 1990-2100, focusing on the combined effects of declining fertility and increasing life expectancy. Demographic winter refers to a structural stage of demographic transition characterized by persistently low fertility, population ageing, and sustained gains in longevity, which may affect population dynamics, economic sustainability, and social protection systems. Data from the United Nations World Population Prospects were analyzed using the Lee-Carter mortality model, with the mortality index projected through an ARIMA (0,1,0) process. Fertility trends were assessed using a cohort-component approach to capture long-term reproductive dynamics. The results reveal a sustained decline in crude birth rates across all countries, with reductions exceeding 60% in several cases and convergence toward very low fertility levels by the end of the century. Simultaneously, life expectancy is projected to continue increasing, generally reaching values between 85 and 90 years by 2100, although at a slower rate than in previous decades. A strong inverse relationship between fertility and longevity was identified, with life expectancy explaining more than 85% of the variation in birth rates. Longevity milestone analyses indicate a high probability of reaching moderate thresholds, while extreme longevity remains uncertain. These findings confirm the consolidation of a demographic winter scenario in South America, characterized by accelerated population ageing, a shrinking working-age population, and growing pressure on pension systems, healthcare services, and long-term care structures. The coexistence of low fertility and increasing longevity reflects a long-term structural transformation rather than a temporary demographic fluctuation. The study highlights the importance of demographic policies aimed at strengthening social protection systems, adapting labour markets to ageing populations, and incorporating long-term demographic projections into public planning.