Two in five (40%) women are saving adequately for their retirement, the lowest proportion ever recorded by the Scottish Widows Women and Pensions Report, which has been tracking the figures since 2006.
Around half (49%) of men are putting enough cash aside for their later years, unchanged from last year.
More than a third (37%) of women surveyed have no private pension, while for men this figure is just over a quarter (27%).
The report urged politicians and the industry to "work harder" to understand the obstacles to building a retirement pot faced by women, who are often forced to prioritise more immediate family needs over long-term saving.
It also uncovered a "black hole" where around a fifth of women were relying on their partner's pension to support them in later life but often they were unclear how their partner's savings and their own would be divided if their relationship broke down.
She said: "They typically earn less and work for fewer years than men which makes it much harder for them to save as much as men."
Scottish Widows' survey of more than 5,000 UK consumers defined people as saving "adequately" if they were putting at least 12% of their salary aside or expecting their main pension to come from a "gold-plated" scheme which guarantees a certain income in retirement, such as a final salary pension.
The proportion of women found to be saving adequately peaked at 50% two years ago, while for men a high of 54% were found to be putting enough money aside in 2009.
Among those who are saving into a pension, the gender gap has reached almost £1,000 a year. Women are putting £2,184 away, while men are saving £3,120.
The report highlighted barriers to women's pension saving at different life stages. The career breaks and shortened working hours women often take as they bear the brunt of childcare responsibilities mean the typical income for a woman in her 30s is £19,200 compared with £28,700 for a man of similar age.
Apart from pension and property investments, women in their 30s are adding just over £1,000 a year to their nest eggs typically, while men of the same age are putting around £1,800 away, the report said.
Even in their 40s , almost one in four (23%) women said they were prioritising financially supporting their children over retirement saving.
Some 19% of women across all ages expect their partner's income to support their own retirement, but the report raised concerns about what would happen if the couple split up. Three-quarters of women (77%) were unsure what their partner would be entitled to from their own pension fund if they were to separate.
The report said: "Setting aside the considerable emotional trauma involved when a long-term relationship breaks up, this kind of life event represents one of the most significant information black holes in modern British life, and not just for women.
"Financial advisers should encourage cohabiting and married couples to become jointly responsible for and aware of financial planning, including their combined worth and retirement entitlements, not only to encourage female engagement but also to help mitigate the potentially severe monetary effects of separation."
The report also suggested women feel less confident about savings products than men. Men are more likely than women to have money invested in a stocks and shares Isa, which can offer better but more "risky" rates of return than a cash Isa. Some 17% of men said they had a stocks and shares Isa, compared with 11% of women.
Meanwhile, women were much more likely than men to have failed to save into a private pension because they do not understand how they work. Some 15% of women who had not saved into a pension gave this reason, compared with 7% of men.
More than half (53%) of men surveyed know what an annuity is, compared with 41% of women. An annuity is a fixed yearly retirement income which people buy with the pension pot they have accumulated over their working lives.
More than 1.7 million men and women have been placed into workplace pension schemes as part of Government moves to head off a looming retirement savings crisis as people live for longer but fail to put enough cash aside for their old age.
So far, around nine in 10 workers who have been placed into a pension under automatic enrolment are staying in rather than opting out as the five-year initiative rolls out.
Lynn Graves, head of business development at Scottish Widows, said: "The pensions industry, Government and employers need to work together to raise awareness of the unique lifestyle pressures that take their toll on women's savings at different ages and help women prioritise their pensions.
"Initiatives such as auto-enrolment are fundamental in helping the nation's workers to think about saving, but women outside the workplace need greater access to information and guidance about other retirement options."