Childlessness has reached record levels among a generation of women wrestling with the pressures of careers, mortgages and rocky relationships.

One in five women are now reaching middle age without having had children, new official figures showed today.

The proportion of women who go without having a family has reached historic levels last seen in the generation born just after the First World War, whose peak childbearing years coincided with times of depression, another world war, and post-war austerity.

Now, analysts said, many women have chosen to put family second to careers that would have been out of reach of their mothers and grandmothers.

Others have delayed having children for too long either because they cannot face the high costs or because they are uncertain about the commitment of live-in male partners.

The figures from the Office for National Statistics, prepared from birth registration records and large-scale household surveys covering many years, showed that one in five of the generation of women born in 1964 have not had children.

The 1964 generation have now reached the age of 46, at which they are officially counted as having completed their childbearing.

The 20 percent childlessness rate has been matched only by women born in 1920, who were teenagers during the depression of the Thirties, reached adulthood during World War Two when many men were away fighting and high numbers were killed, and who were 30 by the end of the austerity years that followed the war.

Women born later were part of the generation of baby-boomers whose birthrates reached record levels during the Fifties and Sixties. Only one in ten women born in 1945 was childless.

The ONS analysis said that 'the level of childlessness for women born in 1964 is at a 44-year high and comparable with that of women born in 1920.

On average, each woman who reached the age of 45 last year had 1.9 children, compared with 2.4 on average for their own mothers - the generation born in 1937.

Jill Kirby, director of the centre right think tank Centre for Policy Studies, said: 'There is increased pressure on women to be breadwinners and too often they have either had to postpone families or, sometimes, lose the opportunity to have children.'