Families where mothers earn as much as or more than fathers are no more likely to split up than those where mothers earn less, according to new research published today. In fact, the evidence shows that having a mother who earned more than her male partner made these couples more stable.

In their article, published in the journal Sociology, Professor Shireen Kanji and Dr Pia Schober analyse data from 3,944 heterosexual British couples enrolled in the Millennium Cohort Study. Tracking these couples as their first child aged from eight months to seven years, they look at whether the probability of relationship breakdown was different for couples where the mother was the higher-earning parent (defined as her earning more than 120% of the father’s income).

They found that there was no significant difference in the risk of marital separation among these couples – and that in some situations, having a higher-earning mother seemed to make couples more stable in the early years of their child’s life.

For instance, in the period when their first child was between four and seven, the risk of divorce was 80% lower for married couples with mothers earning more than for marriages where fathers were the higher earners. This effect was also seen in this period in unmarried couples living together (cohabiting), where those with mothers earning more were 60% less likely to separate than those with fathers earning more. A similar, less significant effect was seen in the period between the child’s third birthday and their first day at school.

She works hard for the money

Asked for comment on the study’s findings, Professor Kanji reflected on the fact that macroeconomic, quantitative studies of wage effects on relationships have usually been pessimistic about the chances for heterosexual families whose highest-earning parent is the mother.

“Quantitative social science is very conservative in its outlook,” she said. “Many studies are preoccupied with the stability of couples, the threats to couples of women’s independence and the negative effects for children of not living with both parents.”

“Fears about women’s higher earnings reflect theories, and anxieties, that if women had the financial means they would not stay with men so that women’s dependency holds couples and society together.”

Kanji also stressed that the study included cohabiting couples, whose overt presence in national data sets is a relatively new phenomenon.

“It is easy to forget how new the phenomenon of recorded cohabitation is in the UK and how much attitudes to cohabitation have changed. Cohabitation is socially acceptable today, in 2012 there were 5.9 million people cohabiting in the UK, but this has not always been the case.”

“As a result, surveys rarely asked specific questions about cohabitation. This situation has now changed, presenting researchers with the possibility to study dissolution in different types of relationships.”

“According to the data we used in our study about 36% percent of new births to couples in the Millennium were to parents who were cohabiting. If we want to understand some of the dynamics of family life, we need to study cohabiting, married and lone parents.”

The authors caution that its findings do not signal a new wave of gender equality. This concern was echoed by Lynn Prince Cooke, professor of social policy at the University of Bath, who also raised some questions about the study’s methods – drawing attention to the fact that as the sample’s children aged, many of the couples shifted towards a male breadwinner model.

“The percentage of female breadwinning couples declined across the period, to be just 5% in the final cohort sample,” she said.

“When you have such small cell sizes, you can get very large effects, even statistically significant ones, but they must be viewed with caution. It can indicate a special group that is not captured by the existing variables – perhaps a husband with health problems, or a disability that would both predict the wife to be the primary breadwinner, and perhaps a lower risk of either partner terminating the relationships (out of dependence or guilt).”

These concerns aside, the study’s findings will reframe the way that social scientists use data to investigate the reasons families stay together or break up – research Kanji says we still badly need: “Expectations about women’s roles in society are still very traditional in the UK. We need more policy-related research into how it can be possible for men and women to take on a wider range of roles than has until recently been the case.”