Research suggests high-earning mothers could be the secret to happier families.

The outdated notion that increased female independence would undermine traditional family structures has been turned on its head, thanks to new research.

Heterosexual couples in which the woman earns at least 20 per cent more than her male partner are less likely to split up, according to a study published in the journal Sociology.

The findings, which took into account almost 4,000 British couples, claim that couples who earned approximately the same were no more likely to split up than those where the father earned more.

However, couples with nursery-age children are up to 80 per cent less likely to separate if the woman is the main earner in the family.

Co-author of the research, Dr Shireen Kanji, of the Leicester University School of Management, said: “Sociological and economic theories have long predicted that women’s increased economic independence would undermine the institution of marriage.

“Previous studies of married couples in the UK provided evidence that women’s higher earnings increased the risk of divorce.

“We found that influential theories that a woman’s higher earnings elevate the risk of divorce are unfounded amongst contemporary parents in the UK.

“Our findings show that equal earning, and a mother being a main earner, are not destabilising influences on relationships, even at an intense time of childcare responsibilities.”

While the evidence points to the fact that equality could actually be the key to a happy relationship, it also highlights the well-documented impact that childbearing has on women’s careers.

Researchers found that six per cent of mothers with children aged under one year earned at least 20 per cent more than their partners, but this figure fell to just under four per cent by the time the child was five years old.

Similarly, 11 per cent of mothers with children under one earned a similar salary to their male partner, compared to just over four per cent by the time the child is five.

Researchers said the study reflects the fact that “the potential for women to earn the same or more than a male partner has increased rapidly in recent years, in line with a steep rise in mothers’ labour force participation and women’s educational performance overtaking that of men.”

But they warned “these results do not necessarily signal a victory for gender equality.

“Mother-main earner and equal-earner couples are not at a higher risk of splitting up, but they do overwhelmingly change to a male-breadwinner model [over time].

“The proportions of couples in which the mother is the main or equal earner decrease significantly as the first child ages.”

Recent figures from the Office for National Statistics (ONS) show that the gender pay gap has widened for the first time in five years – from 9.5 per cent to ten per cent in 2012.

Once women have children they are often forced to make the choice between family and career, thanks to a lack of flexible working hours, expensive childcare and the current inequality in parental leave.

As women have to take on part-time work, often in poorly paid industries, it’s no surprise then that female breadwinner families start to disappear.

Perhaps that happiness will always be short-lived if we can’t find a better solution to retaining women in the workplace.