Twenty one per cent of women believe they will miss out, compared with 14 per cent of men. Fewer women believe they will make the equivalent of the 35 years of National Insurance (NI) contributions needed to qualify.

Nearly half (49 per cent) of those who think they will miss out believe they will do so as a result of taking career breaks to raise children, although 20 per cent say they will not meet the target due to long-term illness.

For those who fail to clock-up the necessary 35 years in employment, additional years can be bought in voluntary contributions, or can be credited to those who receive Jobseeker’s Allowance or Employment and Support Allowance. People who claim child benefit for children under the age of 12, those who are unable to work through illness, and carers can also claim added years.

The research found that only 14 per cent of adults who believe they won’t reach 35 years in employment will make voluntary additional NI contributions, to ensure they qualify for the full State Pension.

Prudential’s research was conducted among people born after 6 April 1950 and found that 27 per cent of those aged 55-plus were not aware of the State Pension reforms. This figure rises to 53 per cent, among the total adult population. There is also confusion around how much the new State Pension will be worth. On average, those surveyed believe it will be worth £125 a week, compared with the actual £155 a week, although one in nine (11 per cent) thought it would be £170 a week.

Tim Fassam, pensions policy expert at Prudential, said: “The launch of the flat rate State Pension in April 2016 is designed, in part, to make it easier for people to understand how much they will receive from the State, in turn enabling them to better plan for their retirements.

“But inevitably, due to the changes to the rules on eligibility, there will still be differences in what people receive. It is therefore important for everyone to obtain all the relevant information so that they can make an informed decision, if they need to make up additional qualifying years through working longer or making voluntary contributions.

“However, people should not rely on the State Pension alone. Saving as much as possible as early as possible in your working life, and seeking professional financial advice in the run-up to retirement, will help to ensure that you are best placed to make the most of your savings when you’re ready to stop working.”