Caring for young children is a major factor preventing women from providing for their old age, a study suggests.
Having a child can scupper your pension
According to the survey, 50% of women who are saving for retirement stop when they have a child.
As a result, only 15% of women who have children aged under five are paying pension contributions.
Scottish Widows, the insurance firm that commissioned the research, said that giving up work after the birth of a child was a key factor.
Ian Naismith of Scottish Widows said: "When you have a pensions system that overlooks the needs of women, it should come as no surprise to find so many women living on low incomes in retirement."
He also pointed to changing financial priorities for women when they first have children as a reason for their sudden drop in pension saving.
The problem of how to lift people out of poverty when they retire is currently the subject of intense scrutiny.
At the end of November, the government's Pensions Commission, led by Adair Turner, will publish its final recommendations on how the nation's pension provision could be improved.
One idea has been put forward by the National Association of Pension Funds, which has been campaigning for what it calls a "citizens' pension".
This would be funded by combining the current state pension and the second state pension, along with the money the government spends on funding contracting-out arrangements and pension credits.
The NAPF argues that this would provide a much higher level of uniform state pension which could be given to all pensioners, regardless of national insurance contributions, thus particularly benefiting women.
The issue of women being particularly badly off in retirement was highlighted last month by Pensions Secretary David Blunkett.
He told the Labour Party conference that low pension provision for women was a scandal.