Fertility Decline and Changing Population Structure in India

India is undergoing one of the most consequential demographic transformations in its modern history. Sustained fertility decline, accompanied by improvements in survival and changes in family formation, has shifted the country from a predominantly youthful population towards a more mature age structure. This paper examines the trajectory, determinants and structural consequences of fertility decline in India, with particular attention to regional disparities, demographic momentum, the changing balance between children, working-age adults and older persons, and the implications for development policy. The study adopts a descriptive, analytical and comparative secondary-data design. It draws primarily on the National Family Health Survey (NFHS), Sample Registration System (SRS), official population projections for 2011–2036, United Nations World Population Prospects 2024, the India Ageing Report 2023 and relevant peer-reviewed demographic literature. India’s total fertility rate declined to 2.0 children per woman in NFHS-5 (2019–21), while the SRS Statistical Report 2022 also records a national TFR of 2.0. However, substantial inter-state differences remain. Fertility decline is progressively narrowing the base of the population pyramid, expanding the relative weight of the working-age population and accelerating population ageing. Official projections indicate that the proportion aged 0–14 may fall from 30.9% in 2011 to 20.1% in 2036, while the population aged 60 and above may rise from 8.4% to 14.9%. The paper argues that India’s demographic challenge is no longer adequately described as population growth alone; it increasingly concerns the management of demographic diversity, labour-force absorption, reproductive choice and ageing.