An ageing and declining population: from 10 billion to bust
20 November 2025
By the mid-2080s, the global population will start decreasing. Policies must shift to adapt before it is too late.
Unprecedented, catastrophic, a crisis. These are all descriptors that have been used in headlines about global population decline. With the United Nations (UN) issuing warnings about falling birth rates – particularly in high- and middle-income countries – is it something we should be worried about?
The other side of the coin is an ageing population – which may be a more tangible concept because it is more visible. In 2018, the number of people over 64 surpassed the number of children under five for the first time in history, and this demographic shift is creating consequences both for economies and for health systems.
What is population decline and how is it resulting in an ageing population?
Population decline is defined as prolonged below-replacement fertility rates. What this essentially means is that the number of babies being born in a country is less than the number of people dying, and the levels of immigration are not high enough to fill in the gap.
The current global fertility rate is 2.25 live births per woman, down from 3.31 in 1990. This is only just above the replacement level of 2.1, which is needed to maintain a steady global population. However, in more than 50% of the world’s countries, fertility rates have fallen below 2.1. And in nearly 20% – including China, Italy, South Korea and Spain – rates have fallen to ultra-low levels: only 1.4 live births per woman.
By the end of the century, there will be more people over 65 than under 18.
These statistics indicate that the global population will peak at 10.3 billion by the mid-2080s and then decline, falling to 10.2 billion by the end of the century – and there will be more people over 65 than under 18.
This is where the ageing population comes in. While there was a baby boom from the early 1940s to the 1960s, those birth rates have not been maintained. The number of people over 65 grew from approximately 126 million in 1950 to almost 809 million by 2023 – an increase of over 540%. Baby boomers are now entering (or already in) their retirement years, and the oldest among them are now in their mid-80s. This is having a huge impact on global economies and health systems.
Why is the global population in decline?
An increasing number of people are starting families later in life, which means they often go on to have fewer children. For example, data from 2016 show that approximately 22% of births were to mothers over 35; in 1980 that figure was just 6%. The reasons behind this may have to do with increased educational and career opportunities for women and the higher costs (including for childcare) associated with having a family. Indeed, data from the UK show that, in 2022, annual nursery fees were £2,200 higher than they had been in 2010.
Gender inequality may also play a role. For instance, in South Korea the gender pay gap is among the most severe of all Organisation for Economic Co-operation and Development countries. And South Koreans work some of the longest hours of any high-income country; these factors may deter women who want to have children from working. There is also increasing resistance to gender equality among men and a push towards women maintaining more traditionally gendered roles. This has fuelled the rise of the 4B movement, which advocates for women to reject marriage, childbirth, romance and sexual relationships. In a country where, in 2024, fertility rates were among the lowest globally – an average of just 0.75 births per woman – this cultural divide may prove to have a considerable long-term impact.
And while it is widely accepted that financial strain can be a core reason to defer having children, other issues are at play too, including job insecurity, a lack of support networks, or simply not having met the right partner. Sociologists have also noted a shift in people’s perceptions about having children; whereas starting a family was once seen as a cornerstone event – something people did as they embarked on adult life – it is now seen as a capstone event, or something that you do once you have achieved all your other goals.
What are the consequences of population decline and an ageing population?
As the proportion of people over 65 – traditional retirement age – grows, the workforce will shrink; and lower tax revenues, combined with higher outgoings to support pension systems, will likely put a huge strain on already stretched government budgets.
Another consequence may be workforce shortages, especially in healthcare and social care. In many countries, the number of people leaving the workforce exceeds the number entering it. And while there are expected to be 53.9 million healthcare workers globally by 2030, that number will be far from the 80 million needed to meet demand. The shortfall is likely to be compounded by higher demand for healthcare, social care and long-term care, increasing the workload of a shrinking workforce and resulting in burnout and further attrition of workers.
In addition to the interplay between population decline and an ageing population, life expectancy has continued to rise – but healthy life expectancy has not. This is often due to the growing prevalence of multimorbidity – including coexisting conditions such as cardiovascular disease, diabetes and mental health conditions – which has been found to result in increased healthcare utilisation and expense, and reduced quality of life, particularly as populations age.
Ultimately, these factors may lead to unsustainable health systems and low economic growth, which will be shouldered by a smaller workforce with greater financial responsibilities to support an ageing population.
Starting a family was once seen as something people did as they embarked on adult life. It is now seen as something you do once you have achieved all your other goals.
What is being done to address population decline?
According to the UN, 62% of countries with fertility rates below the replacement level have adopted policies to increase birth rates, including family allowances, parental leave, tax incentives and flexible work schedules. While many of these are encouraged by the UN Population Fund (UNFPA), as they empower people to make decisions about having a family without the worry of economic and social barriers, the UNFPA also warns against overly simplistic or coercive policies that could violate human rights, such as baby bonuses and fertility targets.
In Austria, a government reform increased parental leave from 12 to 24 months, which led to a 5.7% increase in the likelihood of parents having another child. In Germany, policies that aimed to create a substantial number of subsidised childcare slots for children under three demonstrated that just a 10% increase in funding for childcare resulted in a 2.8% increase in the birth rate. In the UK, an upcoming review will look at parental leave and pay entitlements with the aim of better supporting parents to balance their home and work lives.
Implementing policies that help prevent age-related poor health may also support efforts to achieve longer healthy life expectancy and reduce strains on health systems. The Lancet Commission on dementia prevention, intervention and care has identified 14 modifiable risk factors that, if eliminated, could prevent or delay up to 45% of dementia cases. These risk factors occur throughout the life cycle and include hearing loss, social isolation and low levels of education. While multifaceted and complex, many of these factors could be addressed with more holistic approaches to health and care. Unfortunately, the latest progress report from the UN General Assembly on its Decade of Healthy Aging initiative revealed that fewer than one third of countries have the resources to effectively implement policies that promote healthy ageing. This shows how much more work there is to be done.
The combination of declining fertility rates and ageing populations may be creating a perfect storm for economies and health systems. With a growing number of people expected to rely on these systems, and fewer people in the workforce to support them, we desperately need proactive policies that address the issue, such as facilitating migration to offset below-replacement fertility levels, supporting people to have families – should they want to – and helping people live healthier and longer lives. As is often the case, there is a delicate balance to be struck; but consideration of these issues must begin sooner rather than later to avoid the risk of an unsustainable future for the next generations.