The number of women aged between 25 and 34 with no children has increased dramatically since 1996, according to the latest census figures.
Nearly 60,000 married or cohabiting women aged between 25 and 34 - some 38 per cent of the total number in this age bracket - are childless, compared to 28 per cent in a similar age category in 1996.
The Central Statistics Office figures released yesterday are contained in Census 2002 Volume 3 - Household Composition and Family Units.
The birth rate trends are likely to fall further, since women are increasingly likely to delay pregnancy, or to have just one child, or none at all.
The number of children aged up to 9 years fell by 3 per cent while those aged between 10 and 19 dropped even more strikingly, down by 11.7 per cent.
The number of cohabiting couples rose dramatically in the years between 1996 and 2002, up from 169,300 to 228,600 - a rise of 35 per cent.
Meanwhile, the pressure on housing is illustrated by the fall in the average number of people living under the one roof, which has fallen from 3.14 in 1996 to 2.95 last year. The figure in Dublin is even lower.
Just 2.59 people now occupy the average home in the Dublin City Council area, though the statistics for outlying council areas are higher.
In Dún Laoghaire/Rathdown, 2.9 people share each house, compared with 3.01 in 1996, while 3.18 people do so in Fingal, down from 3.46 in 1996.
Besides Dublin city, Cork city has the lowest average occupancy record in the Republic.
Just 2.75 people share each house, compared with 2.96 people six years ago.
In 1946, 4.16 people shared each house, though the figure has been in steady decline since 1966 when the statistic stood at 4.01.
The expansion of Dublin's population into surrounding counties is shown by the fact that Ratoath, Dunboyne and Dunshauglin in Co Meath have the highest proportion of families with children.
Housing prices may also partly explain why so many young adults in their 20s and 30s are still living at home with their parents for much longer than before.
The numbers of those aged over 20 still living under the family roof rose by 13.7 per cent in the six-year period, while the numbers of 30-plus year olds living in the family home now stand at 42,500.
The majority of the 277,573 one-person households in the State, which are up 15 per cent, are in Leinster, with 85,004 of those in Dublin and 80,258 spread throughout Munster.
One-person households now make 22 per cent of the total in the State, though south Dublin, despite the flight of children to the suburbs, has the lowest percentage, standing at 14 per cent.
The number of elderly people living alone continues to increase. In all, there are 392,836 pensioners in the State, 113,826 of whom live alone.
The over-70 population now stands at 266,222. Over 33 per cent of them live alone, though the number of women doing so significantly outstrips the numbers of men.
There are 41,299 cohabiting couples with two children, according to the CSO, while 3,745 couples have three children.
Two have more than eight children.
The number of female lone parents stands at 111,205 - just over 34,000 of whom live in Dublin. There are 13,903 lone mothers with four children.
