Children born today could need to work until 75 before they become eligible for their state pension. Rising life expectancy and a low birth rate means that the pension will become increasingly unaffordable. The warning came from think tank the Centre for Social Justice, which called for a range of measures to make it easier to start a family. Failure to act will create a pensions timebomb, it said in a new report. State pension age would need to hit 75 to maintain today's worker-to-pensioner ratio

Britain now needs 250,000 more births every year to maintain a stable population without migration. And a collapsing birth rate means 600,000 women today risk missing out on motherhood, compared to their grandparents' generation Analysis of official figures show that in 1970 there were four working-age people for every pensioner. By 2025 the ratio had already fallen to 3.5 workers per pensioner, and under current trends it is expected to fall to around 2 workers per pensioner in fewer than 90 years.

At the same time, the UK is seeing record low birth rates. In 2024 the UK's Total Fertility Rate - the average number of births to a woman over her lifetime - fell to 1.41, far below the 2.1 children per woman needed to maintain a stable population.

The think tank warns that this demographic imbalance means fewer workers will be supporting more retirees, placing mounting pressure on taxes, pensions and public services.

Edward Davies, Research Director at the Centre for Social Justice, said: "Britain is heading off a demographic cliff edge. When fewer children are born, fewer workers enter the labour force, and the burden of supporting an ageing population falls on a shrinking number of taxpayers.

"If we try to maintain today's balance between workers and pensioners, children in school today could be working well into their seventies before they qualify for a state pension.

"This reflects a catastrophic failure to support the next generation of families. Most young people still want children, but too many feel unable to have them. If we want a sustainable economy and a society that cares properly for the elderly, we must start taking family seriously again."

The Office for Budget Responsibility has also warned that, on current trends, UK public debt could rise to around 270 per cent of GDP by the early 2070s as ageing pushes up spending on pensions, health and social care.

Britain currently has around 13 million people aged over 65, a number expected to rise to over 17 million by 2043, increasing the share of older people in the population from roughly one in five today to one in four within two decades.

The Centre for Social Justice report also found that Britain now needs almost 250,000 additional births per year to maintain a stable population. In 2024 there were 831,075 people turning 50 but just 594,677 births, leaving a "birth gap" of around 30 per cent.

The think tank argues that without a reversal in declining birth rates, younger generations will face growing fiscal pressure as they are expected to fund pensions, healthcare and care costs for an increasingly elderly population.

Its report emphasised that the pension system is funded by current taxpayers, rather than by individuals saving for their own retirement, meaning the sustainability of the system depends on a sufficiently large working-age population.

High levels of immigration have temporarily slowed the demographic shift but cannot solve the underlying problem, as age and fertility rates among migrants also tend to fall over time, the report said.

The report said falling birth rates were largely driven not by smaller families, but by a rising number of women never becoming mothers at all, often because family formation is delayed by economic and social pressures.

Its analysis suggested that around three million women aged 16 to 45 today are projected not to have children under current trends. If motherhood rates matched those seen among their grandparents' generation, that figure would be closer to 2.4 million.

This means that around 600,000 women today may miss out on motherhood compared with earlier patterns of family formation - many of whom had hoped to start families but faced growing barriers to doing so.

The report called for a renewed focus on supporting family formation earlier in adulthood, arguing that Britain must begin addressing the social and economic barriers that prevent people from having the children they hope for.