UK among worst for life expectancy rises
Increases in life expectancy in the UK have stalled and the slowdown is one of the biggest among 20 of the world's leading economies, ONS data shows.
Rises in life expectancy dropped from 12.9 weeks per year for women from 2006 to 2011 to 1.2 weeks per year from 2011 to 2016, its report found.
This increase in life expectancy for women was the lowest of the 20 nations, while for men only the US was worse.
There was also a slowdown in other countries across Europe and Australia.
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Throughout the 20th Century, the UK experienced steady improvements in life expectancy at birth.
This has been attributed to healthier habits among the population as it ages, such as reduced smoking rates and improvements in treating infectious illnesses and conditions such as heart disease.
But in recent years the progress has slowed.
The ONS's analysis found the slowdown in life-expectancy improvement in the UK was most pronounced in women, dropping by 90% from 12.9 weeks per year from 2006 to 2011 to 1.2 weeks from 2011 to 2012 - the biggest reduction in all of the countries it analysed.
For men, this was down 76% from 17.3 to 4.2 weeks.
The ONS said the fall among men was in part due to a significant increase in male life expectancy between 2001 and 2011.
As of 2016, a female baby born in the UK would on average be expected to live until 82.9, while a boy would be predicted to live until 79.2.
Sir Steve Webb, former Liberal Democrat pensions minister and director of policy at the insurance provider Royal London, said: "The UK has slumped from being one of the strongest performers when it comes to improving life expectancy to bottom of the league.
"There is a real human cost behind these statistics and we urgently need to understand more about why this is happening."
Prof Martin McKee, professor of European public health at the London School of Hygiene and Tropical Medicine, said he and other academics had for some time been voicing concern about the slowing rate of improvement in life expectancy.
He said the data refuted one of the criticisms of their work - that the UK's slowdown was not unusual compared with other countries.
Prof McKee said: "It is not possible, with these data, to draw a conclusion about the reasons why the UK is performing so poorly.
"Our previous research has provided some pointers, suggesting the need to look in more detail at some consequences of austerity.
"What is in no doubt is the importance that the research needed to explain what we are now seeing is undertaken as soon as possible."
By BBC News health editor Hugh Pym
Life expectancy has been rising in recent decades - but from 2011 the rate of increase started to slow in many countries.
Now we know that slowdown has been more pronounced in the UK compared with several other leading economies. So the question arises: Are there factors peculiar to the UK at work?
Some academics argue that government austerity policies must have played a part, for example cuts in social care budgets in England.
They are calling for a parliamentary inquiry with experts giving evidence.
Ministers say no such causation can be proved.
Some will point out the US has seen a similar slowdown with a very different set of economic policies.
This ONS report is the first such international analysis for a while and raises big questions about health outcomes and government policy in the UK.
The ONS also analysed mortality rates - the number of deaths divided by the population - across the UK nations and found a similar slowdown in improvement between 2011 and 2016.
For men, the improvement slowed most in England and Wales, though progress has also stalled in Northern Ireland and Scotland.
For women, mortality rates increased slightly in Wales and showed no improvement in Northern Ireland.
In England and Scotland, the mortality rates for women fell slightly.
The UK was also at the bottom of the table for life expectancy improvements for men and women at 65 years old.
However, Japan saw a big improvement, while there were also increases for the Scandinavian countries such as Norway, Denmark and Finland.
A Department of Health and Social Care spokeswoman said: "These latest stats show that life expectancy is increasing and we are committed to helping people live healthier lives.
"The recent trends in life expectancy and mortality in the UK are also evident in a number of countries across Europe, North America and Australia - we want to understand these changing trends, which is why we have asked Public Health England to review this.
"As part of our long-term plan for the NHS, we are increasing funding by an average 3.4% per year - meaning that by 2023-24 it will receive £20.5bn a year more than it currently does."