Choosing to cohabit rather than marry can more than double a woman’s risk of becoming a single mother by the time her child is five, according to new research.
The increased risk is consistent regardless of education or income, a study of 15,000 mothers found.
Academics put the pattern down to an inherent difference in the way men and women approach cohabiting relationships compared with marriage.
“Women who cohabit should not assume that their partners are equally committed,” according to a new collection of studies from relationship experts in the UK, Europe and America.
“Women commit when they move in together, whereas men tend to commit only when they decide on a future together.
“Most couples slide into cohabitation without making such a clear decision.”
The findings come in a new collection of studies co-edited by Harry Benson of the Bristol Community Family Trust.
In his introduction, Mr Benson says public policy has until now assumed that family breakdown is “unavoidable” and has focused on “how to manage” the consequences.
But, he writes: “Many families clearly do come through difficult times intact. It is perhaps little known that, even today, most UK marriages still last a lifetime”.
He calls for “an overall strategy geared towards stemming and turning back the rising tide of family breakdown”, including the provision of relationship education.
A Government-commissioned report has also acknowledged a “higher rate of breakdown in relationships” among cohabiting couples.
The report warned that the effects of family breakdown on children could be “enduring”, lasting well into adulthood.
Leading family judge Mr Justice Coleridge warned last month that marriage urgently needed to be reaffirmed as the “gold standard” of relationships.
He said an “epidemic” of family breakdown was damaging children, adding that “re-emergence of a public attitude which is anti-relationship destruction, a new stigma perhaps, could do a lot to stem the flood”.