According to the Office for National Statistics the number of families bringing up children has grown by 300,000 since the mid 1990s despite evidence that people are putting off having children for career or financial reasons.
There are now 7.7 million households in which children are growing up in the UK.
And even the size of families is virtually unchanged in that time despite an expectation that couples will have fewer children than their parents.
The traditional image of a family with 2.4 children may be a thing of the past, but the number of children being brought up in a household is little changed in half a generation. In 1996, the earliest date for which comparable records are available, the average number of dependent children in a family stood at 1.8 per household and last year it stood at 1.7.
Separate research suggests that more than 40 years ago the average family had only two children.
Although the number of large families has fallen markedly in recent years, the UK still has some of the largest families in Europe.
Last year there were just 1.1 million households with three or more dependent or 15 per cent of the total – more than twice the proportion in Italy and Portugal and three times that in Greece and Spain.
In 1996 the proportion of families with at least three children in Britain was 17 per cent.
Across Europe only France, Ireland, Finland, Belgium, Cyprus and the Netherlands have more.
The largest families are concentrated in inner city areas with higher proportions of immigrants, according to the ONS.
In Tower Hamlets, east London, where a third of the population are classed as of Pakistani or Bangladeshi ethnicity, almost three out of 10 families have at least three children.
Although unmarried couples are now more likely statistically to have children than married couples – a reflection of the fact that they tend to be younger overall – most children are still being brought up by married couples, as they tend to have larger families.
Karen Gask, who compiled the report for the ONS, said: "The number of one-child families is increasing, but that is partly because of women delaying having children and the changing make-up of families.
"For example, we know that cohabiting and lone parents are less stable than married-couple families, so some people may have one or two children, then break up.
"More people are going on to higher education, so that is delaying people settling down and getting married. Some people speculate that they are driven by a desire to set up home and afford a mortgage.”