Britain’s population is not replacing itself. For the fourth consecutive year, the Total Fertility Rate (TFR) has set a new record low, down 22 per cent in a decade, and marks an ongoing shift in the future of Britain’s population.

Every 100 women alive today will produce only 66 daughters and 44 granddaughters, meaning that without migration each generation will be approximately a third smaller than the one before. The compound effect of this over decades is not a gentle shrinkage, but a structural transformation of the country.

An ageing nation will place a heavy burden on the next generation. It is the working-age population that funds pensions, staffs our public services, pays taxes and drives economic growth. The size of that cohort is declining relative to the retired population. The Old Age Dependency Ratio has already deteriorated from 4 workers to every 1 pensioner (4:1) in 1970 to 3.5:1 today. This is projected to reach 2:1 within a generation. The CSJ’s previous analysis shows that to maintain even today’s ratio the state pension age would need to rise to 75 by 2093.

This report follows the structure of the Office for National Statistics (ONS) data release, bringing together a broad set of findings as they appear in the data to build a picture of declining fertility and other adjacent issues.

Headline Findings

• The TFR has fallen from 1.79 in 2015 to 1.39 in 2025, a collapse of 22 per cent in a decade, and now 34 per cent below the replacement rate of 2.1.
• Since 2012’s peak of 729,674 births, annual births have fallen by just over 144,000, a reduction of 20 per cent, despite the population growing substantially.
• The average age of a mother is now 31.1 years old, and the average age of a first-time mother has risen to 29.6. In 1975, the average mother was 26.4 years old.
• Fertility among women under 30 has collapsed over the last 20 years. The under-20 birth rate has fallen 75 per cent since 2005; the 20-24 rate is down 50 per cent; the 25-29 rate has fallen 27 per cent.
• Wales has a TFR of just 1.33, one of the lowest in the developed world. Cambridge (0.95), Brighton and Hove (0.97) and Islington (0.99) recorded fertility rates below 1.0 in 2024.
• More than a third of births (34.6 per cent) in 2025 were to mothers born outside the UK, up from 20.8 per cent in 2005.
• In 2025, 53.2 per cent of births were within marriage, compared to 91 per cent of births in 1973.
• Deaths are expected to exceed births in England and Wales from mid-2026, making natural population growth negative for the first time in the modern era.
• On the Department for Education (DfE)’s central projection, England will have approximately 1,150 more primary schools than it has children to fill them by 2030. This is the equivalent of 7 per cent of primary schools needing to close within  a decade, which places more than 34,700 jobs at risk in the primary and nursery school sector.