IN THE 21st century, demographic transition, not an esoteric fact any more, has become a critical issue for policymakers and economists worldwide. The process affects every aspect of society, from the labour market and economic growth to healthcare systems and social security to the extent that supranational organisations such as the World Bank, the Asian Development Bank, etc are paying keen attention to the overall phenomenon. For emerging countries such as Bangladesh, understanding demographic transition is particularly important.
Demographic transition is a concept that describes the transformation of a country鈥檚 population structure over time, typically moving through four distinct stages: from high birth and death rates to lower birth and death rates as a country develops economically. This process, first observed in Europe during the Industrial Revolution, has profound implications for a country鈥檚 economic development, social structure and environmental sustainability. The theory of demographic transition was first proposed by Warren Thompson in 1929 and it has since become a cornerstone of population studies. Typically, this process is divided into four stages:
Stage 1 鈥� Pre-transition: Characterised by high fertility and high mortality, leading to a stable but low population growth rate. This stage was common globally before the 19th century.
Stage 2 鈥� Early transition: Mortality rates begin to decline because of improvement in health care, nutrition and sanitation while birth rates remain high. This leads to a rapid increase in population growth. Many developing countries experienced this stage in the mid-20th century.
Stage 3 鈥� Late transition: Birth rates start to fall, catching up with the declining mortality rates. Population growth slows down and the age structure begins to change, with a smaller proportion of young people and a growing share of the elderly. This stage is where many emerging economies find themselves today.
Stage 4 鈥撎� Post-transition: Both birth and death rates are low, leading to a stable and aging population. Many developed countries, particularly in Europe and East Asia, are in this stage.
As of 2023, the global population has reached approximately eight billion, with significant disparities in growth rates between regions. The United Nations estimates that the global fertility rate has declined from five children per woman in 1950 to around 2.4 in 2020, with projections suggesting that it could fall below the replacement level (2.1 children per woman) by the mid-21st century.
Europe and East Asia are experiencing some of the lowest fertility rates globally, with countries like Japan (1.34), Italy (1.27) and Germany (1.54) struggling with aging populations and declining workforce members. The economic implications are profound, with potential labour shortage and increased pressure on pension and health care systems. In contrast, Sub-Saharan Africa remains in the early to middle stages of demographic transition, with a fertility rate of 4.6 children per woman as of 2023. This region is expected to contribute significantly to global population growth in the coming decades, potentially doubling its population by 2050.
While this presents opportunities for economic growth, it also poses challenges in terms of providing education, health care and employment for a rapidly growing youth population. Countries such as India and Bangladesh are in the late transition stage, with fertility rates declining but still above replacement level. India鈥檚 fertility rate, for example, stood at 2.0 in 2023, down from 5.9 in 1950. These changes are accompanied by shifts in the age structure, leading to a growing working-age population that could, with the right policies, drive economic growth.
The global decline in fertility rates is one of the most significant demographic shifts of the past century. According to the World Bank, the global fertility rate fell from 4.98 in 1960 to 2.43 in 2021. This decline is largely attributed to improved access to education, mass awareness, particularly for women, an increased use of contraception, urbanisation and changing cultural norms around family size. In parallel, life expectancy has risen dramatically, owing to miracles of medical sector and improved way of life. The global average life expectancy increased from 52 years in 1960 to 72.6 years in 2021, with significant regional variations. For instance, life expectancy in Sub-Saharan Africa is 64.5 years, compared with 80.2 years in Europe and Central Asia. The trends have led to an ageing global population, with the proportion of people aged 65 and over expected to double from 9 per cent in 2020 to 16 per cent by 2050.
Japan is a textbook example of a country in the post-transition stage. With one of the highest life expectancies in the world (84.8 years in 2021) and a fertility rate well below replacement level, Japan鈥檚 population has been shrinking since 2011. The country faces severe challenges related to its ageing population, including labour shortage, increased healthcare costs and a shrinking tax base.
On the opposite end of the spectrum is Nigeria, which represents a country in the early transition stage, with a high fertility rate of 5.2 children per woman as of 2023 and a rapidly growing population. The country鈥檚 population is projected to reach 400 million by 2050, making it the third most populous country in the world. Nigeria鈥檚 demographic profile presents both opportunities and challenges: a large working-age population could drive economic growth, but only if accompanied by investments in education, health care and job creation.
As for Bangladesh, it is in the late transition stage. With a fertility rate of 2.1 children per woman as of 2023, down from 6.3 in 1971, the country has made significant progress in reducing population growth. However, challenges remain, particularly, in managing the aging population and ensuring that economic growth is inclusive and sustainable. Bangladesh, with a population of more than 169 million as of 2024, is at a pivotal point in its demographic evolution, experiencing changes that could either propel it towards sustained economic growth or create significant social and economic hindrances.
The global journey through demographic transition is a powerful reminder of how deeply interconnected our world has become. As countries move through different stages of this transition, the ripple effects are felt far beyond their borders, influencing global economics, migration patterns, and even geopolitical stability. The contrast between ageing populations in Europe and East Asia and the youthful, rapidly growing populations in Africa and South Asia underscores the diverse challenges that lie ahead.
However, this diversity also presents a unique opportunity. The demographic shifts occurring today will define the next century, but how we respond to them will determine whether we witness global prosperity or growing inequality. The urgency for international cooperation has never been greater as countries must learn from one another, sharing best practices and innovative solutions.
As we stand at this critical juncture, the question for policymakers and global leaders is clear: will we seize the moment to create a more balanced, sustainable future, or will we allow these demographic divides to widen, risking instability and conflict? The choices made now will echo for generations to come.
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Galib Nakib Rahman ([email protected]) is an engineer-turned-finance enthusiast.
