The institute’s Continuous Mortality Investigation (CMI) said life expectancy for men and women aged 65 has fallen by around five months to 19.8 and 22.4 years respectively since March 2018.

Moreover, its findings suggest that mortality improvements peaked in 2004 for males, and 2006 for females, with the decline in longevity thought to be a trend rather than a blip.

CMI mortality projections committee chair, Tim Gordon, said improvements were typically over 2% per year between 2000 and 2011, but have since fallen to around 0.5%.

“It’s now widely accepted that mortality improvements in the general population since 2011 have been much lower than in the earlier part of this century,” he continued.

“The causes of the slowdown, and whether these current low improvements will persist, remain a subject of considerable debate.”

The projections are based on the latest CMI_2018 model, which uses data for 1978-2018, and has been adjusted to place more weight on recent lower mortality improvements.

Gordon added: “The model reflects increasing evidence that the lower level of improvements may be due to medium or long-term influences, rather than just short-term volatility.”

It is thought that the latest longevity decline could put pressure on the government to reverse planned increases to the state pension age. 

Meanwhile, professional services firm Aon has calculated that the latest fall in life expectancy could slash average pension scheme liabilities by approximately 2.5%

However, the exact impact is expected to depend on the age profile of an individual scheme’s members and the valuation assumptions used.

“Insurers and reinsurers have continued to evolve their pricing models in light of emerging data,” Aon senior partner, Martin Bird, said.

“We expect these updates to the model to be routinely adopted, reflecting strong evidence that underlying longevity improvements are materially lower than seen in the first decade of this century.”