The number of deaths in the UK is likely to outweigh the number of births in 2026, marking a "turning point" for the country, an influential thinktank has predicted.
The Resolution Foundation expects this to be a long-term trend that could mean "fewer people of working age" and "higher taxes".
It suggests immigration would be needed to make up the numbers. But the change comes as just as UK political parties are locked in a fight over who can best reduce current levels of immigration as the issue rises up the political agenda.
The relative fall in the birth rate will mark a significant break with the past. Numbers previously have exceeded deaths almost every year since the beginning of the 20th century.
But in its outlook for the coming year, the Resolution Foundation said: "2026 may be the first year in a new era when deaths exceed births by an ever-widening margin, forever closing a chapter in the demographics of this country that opened over a century ago."
Although this shift has previously happened temporarily, such as during the COVID-19 pandemic in 2020, this year is likely to mark the start of a lasting trend, it added.
From now on "any population growth we do get is set to come from international net migration", the think tank says. But, it adds, latest data suggests that the number of migrants coming to the UK "is also plummeting, down by three-quarters from its recent peak to around 200,000 a year".
UK births seem unlikely to be able to make up the numbers. In 2023, the total fertility rate in England and Wales was 1.44 children per woman, the lowest on record.
Read more from Sky News:
Government plans new driving rule for over-70s
Chagos deal suffers 'humiliating' defeats in Lords
Be the first to get Breaking News
Install the Sky News app for free
Contentious debates about population control
The change comes as broader contentious debates rage about whether population control could help limit humans' impact on the environment, and on how much the UK needs migration.
Greg Thwaites, research director of the Resolution Foundation, said: "2026 could be a tipping point year as deaths start to outnumber births so that, without immigration, the population would start to shrink.
"This may shift the conversation on migration away from arguments over whether the country is already 'full' and onto whether we want to address population decline.
"However, migration policy, and how much it should prioritise economic growth over other considerations, is likely to remain politically charged."
Taxes likely to rise
Taxes are likely to rise as the number of people of working age decreases, the foundation warned.
Reform UK has been campaigning on policies to boost the number of babies being born on home soil.
According to a poll by YouGov, the cost of having children is the main reason Britons choose to stay childless, far outweighing simply not wanting to have children.
This trend is born out around the world, with a UN report also finding cost are a greater barrier to people having children than the desire not to.
The global fertility rate has been declining almost continuously for the past 50 years.
The Home Office was contacted for comment.