<em>Illustration: John Shakespeare</em>

Illustration: John Shakespeare

Forget The Hunger Games. A much more brutal and devastating battle is raging - the mummy wars. In one corner, the layabout, soap opera-obsessed stay-at-home mum, or SAHM. In the other, the negligent, money-obsessed working mum. Only one mother can win - by tearing shreds off her opponents and generally out-bitching the other.

The prize? Moral superiority as the best kind of mother, woman and human being.

Sound ridiculous? Maybe, but there's an ugly grain of truth in there. What working woman hasn't secretly begrudged the SAHM their easier workload? What SAHM hasn't secretly thought working mums neglect the needs of their kids? We women can be pretty hard on each other, almost as hard as we are on ourselves.

A fresh round of the mummy wars broke out in the US last week, when a former lobbyist turned Democratic talking head, Hilary Rosen, said the wife of Republican presidential candidate Mitt Romney had no basis on which to advise her husband on economic issues because she'd ''never worked a day in her life''.

Ann Romney opened a Twitter account to complain: ''I made a choice to stay home and raise five boys. Believe me, it was hard work.''

And so the old catfight was out of the bag again, attracting a stream of online commentary, a prompt intervention by Barack Obama saying the work choices of candidate spouses were irrelevant and an apology from Rosen.

The mummy wars are obviously a simplification. And not just because the concept ignores the bulk of mothers who contort themselves on a daily basis to juggle family and work. It also assumes that women alone are responsible for their decisions and that they do so based on their innate preference for work or child rearing.

In reality, for many mothers, the decision whether to work is purely a financial one. And it is not a decision they make alone - excluding single mothers - but a negotiated outcome between partners in a relationship.

We need to think about families not as a homogenous unit but as a collection of individuals, who can be deployed in various ways to maximise the wellbeing of the family.

In the same way that economies get rich when individuals specialise in what they are best at and then trade, families are better off when their members specialise where they have a comparative advantage.

Traditionally, men have earned more money selling their labour in the market, so it made sense for them to do so and for women to stay at home to look after the children.

For many women in partnerships formed decades ago when women typically did not go to university and were expected to work as secretaries, teachers and nurses, it made financial sense for the woman to devote her labour to domestic duties, rather than paid work.

For their generation, the Romneys probably made the best economic decision they could - with Ann looking after the children while Mitt sold his labour as a management consultant, eventually co-founding a private equity investment company, Bain Capital, which remains a source of wealth for the couple.

But for couples making the decision today about who should bear primary responsibility for domestic duties, the landscape has changed dramatically.

Today's cohort of young women have more than proved their equal ability to earn degrees and hold high-powered positions.

According to figures from Graduate Careers Australia, women make up 64 per cent of university graduates (but only 34 per cent of apprentices and trainees).

Male graduates continue to earn marginally more than female graduates, on median starting salaries of $52,000 versus $50,000 last year.

But at 96 per cent, today's female graduate earnings are fairly close, compared with a wider overall gender ratio of about 82 per cent.

Something happens to women and their salaries when they enter their 30s and that something is children.

Couples today need to - and are - making more active decisions about who will take time out of the paid workforce to look after their children. Couples must consider which partner has the higher earning capacity and whose career progression and future earning capacity will be most negatively affected by taking time out.

In a sense, because many couples are delaying childbirth until their 30s, partners have had almost a decade to establish themselves in their chosen careers and are in a better position to decide who has the highest skills and career prospects.

Because the market value of women's time has risen so dramatically, it is more likely than in the past that couples will decide to deploy the male partner to domestic duties and keep the woman's salary.

The economics of the family are evolving and where gender policies and quotas fail to deliver, the profit motive will out.

It will take time. It requires governments to keep working to remove tax traps that keep women at home because they would lose more in welfare benefits and tax than they would earn. It ideally requires greater attention to the provision of high-quality and cheap childcare to help in the household production of that most private of public goods - children.

Public debates about the choices families make about which partner will bear the burden of childcare should have the emotion taken out of them.

The perception of mummy wars only plays into the stereotype of women as emotion-driven creatures who are out to get one another. This perception perpetuates one of the most dangerous stereotypes for all mothers - that they are forever transformed by childbirth into hormonally unbalanced basket cases.

Decisions about work and family life should be respected for what they are - largely financial decisions about what distribution of labour will maximise a family's income and wellbeing. It's time to call a halt to the war.

Ross Gittins is on leave.

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