The proportion of children being brought up by married parents has fallen to just 63 per cent, according to the Office for National Statistics (ONS).
The new figures were published online as part of the ONS’ annual Social Trends report and revealed there are 8.3 million dependent children living with married parents in 2009 – a fall of 1.3 million since 1997.
During the same period the number of dependent children, defined as those under 16 or aged up to 18 if they are still in school, in cohabiting households went up from one million to 1.7 million.
Since 2008 the ONS has grouped civil partners with married couples when compiling dependent children statistics so the new figures include some same sex-unions.
The number of civil partnerships formed in 2008 stood at just over 7,000.
The ONS statistics also record a fall in marriage and divorce numbers.
The report says the number of marriages in England and Wales fell for three consecutive years between 2005 and 2007.
In 2007 there were around 231,500 marriages, according to the ONS figures.
Divorces stood at close to 128,500 in 2007, a drop of 3 per cent compared to the previous year’s figures.
Last year the Government admitted that children brought up within a marriage setting are better off than children brought up in cohabiting or single parent families.
An evidence paper, Families in Britain, was produced by the Cabinet Office and the Department for Children, Schools and Families.
It cited evidence showing that seven out of ten young criminals come from single parent homes even though these make up just a quarter of all families with children.
It also pointed out that children from lone parent families do less well at school, while two thirds of such families are poor and a third of lone mothers are depressed.
The paper stated that “an absent parent can be associated with adverse material and emotional outcomes” and “by definition lone parent families are cut off from some family functions.”
Even though the evidence paper concluded that married couples are happier and tend to have higher incomes, while their children do better at school and have fewer emotional and behavioural problems, the paper still stopped short of advancing policies to encourage marriage.
Instead of recognising the significance of marriage it focused on the ‘quality’ of relationships.