Women have been failing again. Failing to reach the top tier of their professions; failing at attaining professional parity with men; failing, specifically, to recover career momentum after having children. Or, to look at it another way, society is failing women: failing to promote them; failing to fully utilise their potential. In any case, there are women, and there is failing.

Reports and figures on the gender pay gap invariably stimulate controversy: headlines and internet memes suggest a simple scenario whereby cackling barons of the patriarchy withhold a chunk of rightful pay from female workers, while other voices insist that the disparity either doesn't exist or is more nuanced than blunt figures might suggest. However you interpret the data, what's interesting is that we never seem to flip the question, and ask why men's lives pan out in the particular way that they do. Instead of asking why women feel pressured to change their lifestyle patterns after having kids, we could ask why men feel pressured not to.

We could try out the assumption that providing one-on-one care for and securing a close bond with one's children is a more desirable lifestyle choice than entering the top earning tier - by which rationale women might be deemed to be doing better than men. Why is the decision to prioritise one's children over one's next promotion inevitably presented as a matter for hand-wringing? What if instead of commiserating with those women whose career paths alter after they become parents, or discussing how they are being "held back", we commended them for prioritising matters other than power and money?

Concerns about what is being done to women by society generally appear in the guise of feminism, but can often seem to push the opposite agenda, by implicitly denigrating women's agency as part of that society.

The assumption that the patriarchy is shutting women out of its best opportunities denies the fact that some of them just might not buy into its model of achievement. After all, the figures we see on depleted earnings post-motherhood include those people who have elected, willingly, to arrange their lives in the way that they have. People in relationships who have small children quickly realise that both partners returning to full-time work can be a false economy once the costs of childcare are factored in.

Anyone who has given birth knows that it takes a little time to recover from; and anyone who has breastfed knows that it can be easier to achieve when the baby is nearby - which factors can mean that it can make more sense for mothers to take on the full-time early care of a child, and the career break that involves. Yes, the ways of parenting and feeding are many and varied. All credit to full-time fathers; mothers who "bounce back" to work within weeks; breast-pumpers, bottle-feeders and all points in between. But perhaps we shouldn't regard it as a shock or a societal disaster for mothers' careers to alter more than fathers' after childbearing. And if a woman's experience of parenthood causes her to restructure her attitude to achievement and earning outside the home, perhaps we shouldn't be so keen to call that a failure - on anyone's part.

Unquestionably, there are issues, of which every family and every single parent is aware, around how sufficient earning can co-exist with childrearing. And the ageist assumption that we all get gradually less useful can make it a daunting matter to scale back on work at any stage. But to present the impact of motherhood as the problem - rather than outrageous house prices, expensive childcare, low pay and unforgiving working hours - just seems like another way of burdening women. And it shockingly undervalues parenting as a contribution to society. There's something terribly skewed about the idea that one is falling back in life by making people rather than making money.

The narrative that women's careers are restricted by parenthood suits a currently dominant idea that femaleness is a bit of an unfortunate lot all round. Women, writes the Guardian columnist Jessica Valenti, live "in a culture that hates them". According to the New Statesman's Laurie Penny, "men grow up expecting to be the hero of their own story. Women grow up expecting to be the supporting actress in somebody else's." And when Sandi Toksvig launched the estimable Women's Equality Party, the headline on her introductory article declared that "Everyday sexism makes women's lives unbearable." Unbearable! All of our lives! While few could possibly deny that real sexism continues to assert itself in many areas, there's also a general picture of female existence out there that's so negative it ends up seeming quite sexist itself. If you raise a girl on the assumption that she won't be listened to; that all that matters is her looks; that she's doomed to only be a supporting character; that THE WORLD ACTUALLY HATES HER - how likely is that she'll learn assertiveness? And if she receives the message that her earning power is the measure of her value, how likely is it that she'll have a positive approach to the inevitable upheavals of motherhood?

It's a strange doublethink whereby we massively sentimentalise and overvalue the having of children, and yet treat parenting itself as some sort of useless limbo state during which all sorts of real - i.e. financial - potential is wasted. Imagine if, instead of fretting over women's economic contribution, we treated motherhood - and fatherhood - as useful work. And imagine if, while we were at it, we queried not just the gender pay gap, but the gender parenting gap. I think our perception of womanhood in general would be healthier for it - and our daughters and sons alike might come to thank us.

Hannah McGill is a writer, critic and broadcaster based in Edinburgh. She writes for Scotland on Sunday, Sight and Sound, The Independent and The Times among other outlets. From 2006 to 2010 she was the artistic director of the Edinburgh International Film Festival.