Women still earn substantially less than men on average, and remain severely under-represented at the top of organisations (there are just 11 female CEOs in the ASX 200 and 13 companies without any female directors).

But business is making change, albeit slowly, as it realises the potential of the "sheconomy".

Women control about 70-80 per cent of the world's annual consumer spending.

It is estimated in an EY report that their incomes will increase from $13 trillion to $18 trillion by 2018.

That $US5 trillion leap is almost twice the growth in GDP expected from China and India combined.

The self-purchasing woman is the new target market for companies from iconic jewellery brand Tiffany's to global drone makers.

As women make gains in the labour force, this demographic will grow.

According to a recent survey from De Beers - which created the "A Diamond is Forever" catchphrase - female self-purchasing is on the rise, especially among 25-to-39 year-olds.

It said Millennials spent $26 billion on diamond jewellery in 2015 and 31 per cent of those purchases were from women buying diamond-only earrings and neckwear for themselves.

But women's economic advancement goes beyond a marketing opportunity.

It has the potential to transform the global economy.

Women could be employed to help build critical infrastructure for developing nations in the midst of economic transition.

In advanced economies, raising the participation of women can offset the economic drag of ageing populations.

The EY report says by the year 2028 women will control about 80 per cent of discretionary spending worldwide, and women will own about a third of all businesses around the world.

Another report by McKinsey Global Institute (MGI) examines the economic implications of the lack of parity between men and women.

It mapped gender-equality indicators for 95 countries - which fall into four categories: equality in work, essential services and enablers of economic opportunity, legal protection and political voice and physical security and autonomy - and found that 40 of them have high or extremely high levels of gender inequality.

The report says if all countries match the rate of improvement of the fastest-improving country in their region, it could add as much as $12 trillion, or 11 per cent, in annual 2025 GDP.

Of course, women already make a far greater contribution than official statistics show.

Seventy-five per cent of the world's total unpaid care - crucial tasks such as child care, caring for the elderly, cooking and cleaning - is undertaken by women.

MGI estimates that unpaid work being undertaken by women today amounts to as much as $US10 trillion of output a year, roughly equivalent to 13 per cent of global GDP.

If we were to measure the value of unpaid child care to Australia's economy in dollar terms, it would be the nation's biggest - estimated at $345 billion, according to a recent PwC report.

Australia's tax system also has gender biases built in.

Since women are more often than not the primary carers of children, partnered mothers, as second earners, face high "effective marginal tax rates".

It's not that they are taxed at a higher rate, but rather they lose welfare benefits if they decide to work again.

Every additional dollar of income kept after income tax is deducted, and the means-tested family tax benefits are reduced.

So there's no incentive to return to work, especially when one has to then account for high-costs of child care.

A recent OECD paper suggested possible solutions to this economic problem including greater financial support for women with kids by applying a higher threshold where payments are phased out, or having lower statutory tax rates to reduce disincentives for all workers.

Although these would come at a big cost to the federal budget they should be measured against the economic benefit of getting more women back to work. When women work, economies grow.

For those worried that womens' participation in the labour force could cause declining fertility rates, here's a not so new idea: why not also have men participate in housework and child care?

That would be a win-win: greater female participation in the labour force and higher fertility rates.

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