Married couples are at their greatest risk of divorcing just before their fifth anniversary, it is claimed.

A study suggests that we tire of our partners far sooner than we did in the 50s, when the danger point was the 'seven-year itch'.

Five decades on more women are pursuing careers - which can place extra stress on a relationship - and divorce has become increasingly acceptable.

The findings emerged in a study of divorce trends in the U.S., Scandinavian countries and in Russia.

Experts believe they will also apply to Britain, which has gone through many of the same social changes.

Researchers found that the 'honeymoon' period for newlyweds lasts less than five years and that disillusionment and disaffection often set in by the end of that period.

There is an added incentive to battle through this period, however. The study showed that those who manage to make it to ten years are likely to remain married for good.

Aiva Jasilioniene, an academic specialising in marriage and cohabitation studies, helped produce the report for the Max Planck Institute in Rostock, Germany.

She said: "Crisis point for the modern marriage is arriving sooner.

"One of the explanations for these changes in divorce risk is that during the first decade of marriage both partners go through crucial life - course transitions and challenging experiences - completion of education, building a career, bearing children and so on.”

"During the later years, the couple have developed strategies to deal with problems they arise."

The decision to remain together could have a more practical basis, however.

Researchers found that after the five-year point of marriage, couples are increasingly deterred from parting by the cost of divorce and of running separate lives.

The findings are likely to shed new light on the state of marriage in Britain, which is at the centre of a growing political argument.

The Tories are proposing tax breaks for married couples, who tend to stay together longer than co-habiting couples and whose children tend to be healthier, do better at school, and go on to better jobs than children from broken or single-parent families.

Other results suggest that those who marry at a younger age are more likely to divorce.

This could help explain our falling divorce rate.

In Britain, women marry at 33 on average, and men at 36 - each three years older than the average a decade ago.

And at the same time, the divorce rate is falling.

Last year, the rate fell to 12.2 in every 1,000 couples. This is the lowest since 1984, according to the Office for National Statistics. The total number of divorces in 2006, 132,418, is the lowest since 1977.