There are so many negatives weighing down the choice to have a child, it’s astounding anyone still does it. Financially it’s the most irresponsible thing a woman can do.

It’s bad for your bank balance, and bad for your career. A child will cost you more than $400,000 by the time she turns 18. And you will have forgone an average $300,000 in wages, thanks to forfeited job opportunities, and the move to part- time work.

Motherhood has always been a costly choice. But for well-qualified and ambitious working women, those costs are substantial. So, why do they do it?

Well, just in case Lindsay Tanner and Wayne Swan have been pondering that very question, a thoughtful member of the public has emailed them the answer. It’s as brief, as it is profound: ”Humans are primarily social creatures, not economic units.”

The anonymous message is one of more than 500 emails, and 380 formal submissions, to the Productivity Commission, during its inquiry into paid parental leave. After months on the road, the final public hearing closed this week.

Now, while many slow down for summer, staff at the commission are settling in to wade through and produce a final report by late February. Pity them – not because of the enormity of the task, but rather the nature of the outpourings.

So intense are the arguments for – and few against – paid maternity and paternity leave, that many Australians who sat down to write a short letter, have instead found themselves writing intimate reams. Among the hundreds of emails – available on the commission’s website – are sad and heart-rending stories about financial pain, and how that burden has ruined family lives.

In a particularly personal account, one woman explains how the small firm for whom she worked sacked her when she took leave to have her second child. With no maternity leave, she says her unemployment was ”a huge strain” on her family, and eventually led to severe post- natal depression, for which she was hospitalised. Feeling overwhelmed, her husband then attempted suicide and was left with brain damage.

Scrolling through these stories is a sobering reminder of how messy family life can be, and how the weight of financial hardship can cause ordinary people to fall apart.

Yet, the choices people make and the sacrifices they accept are humbling. One man compensates for his wife’s lost wage, and lack of paid maternity leave, by taking on a second job at weekends. But what sadness, to see the joy of new parenthood overshadowed by a young father’s exhaustion as he works seven days a week.

Most alarming is the number of women who say they are delaying having a baby. One woman says she’s held off for 10 years, just waiting for a better time financially, but that’s never arrived. Some acknowledge they may even miss out on motherhood.

Other than an argument that taxpayers shouldn’t fund other people’s life choices, the emails, letters and submissions are full of compelling personal reasons as to why the Government should support a paid parental-leave scheme. But right now it looks doubtful the Rudd Government will. Despite saying Australia had to bite the bullet on the leave, and then instigating the public inquiry, Kevin Rudd and his team appear to be wavering.

Early this month Tanner added paid parental leave to that growing list of good ideas that might bite the dust, due to the current financial turbulence. The fact that the Government is frantically trying to stimulate the economy, and yet doesn’t see the mandatory payment of parental leave as a way to help do that, defies logic.

In its interim report, the Productivity Commission recommended 18 weeks’ paid leave, plus an extra two weeks paid paternity leave. It would cost taxpayers $450 million, and employers an additional $75million, annually. The payment is a flat minimum wage of $544.

The interim proposal, as it stands, is complex – possibly too much so. But that’s the point of having an inquiry. Its job is to weed out any unreasonable complexities, and to identify unintended disadvantages.

It is true that not everyone will be better off under the proposed scheme. Single mothers, on a very low income, would be better placed financially if they left their job and lived under the current welfare arrangements. Which they could continue to do, as the proposed scheme would be optional.

It is also true that, while Australia is only one of two OECD countries without mandatory paid maternity leave, our Government is generous to new mothers and young families. The baby bonus, along with Family Tax Benefits and various subsidies, account for considerable support.

But there are two outstanding reasons why we need a government- paid parental-leave scheme.

First, it would ensure that every woman gets at least four months at home with her child. It is hoped many will find a way to stretch that to six – now nearly a third of mothers are back at work by then. Second, the message a paid parental-leave scheme would send about what we value as a nation is profound, and not to be underestimated. It’s an acknowledgment of the dual roles of women, and the complexities in being a mother and worker. It’s a way of saying that no woman should wear the burden of that duality alone.

And at the bottom line, it’s an encouragement for women to flourish.