HOLLY WAINWRIGHT: 'This is what 43 looks like now: 23 and pregnant.'

I would like to draw our collective attention to an extraordinary photograph.

This is Sienna Miller at the British Fashion Awards in London on Monday night. It's not an occasion you're turning up to in jeans and a T-shirt.

Miller wore head-to-toe Givenchy, and used this moment to communicate that she is pregnant. The baby will be Miller's third child, her second with boyfriend Oli Green.

Image: Getty.

She also - maybe intentionally, maybe not - used this moment to communicate something remarkable about the moment we live in.

Because Sienna Miller is 43. And this is what 43 looks like now, for some. It looks more like 23, and pregnant.

Let's be clear. This is not a hot-take about women in their 40s having babies. I did that myself, a while back, and thank God. And this is not about what Miller is wearing, which is fabulous in every way.

Watch: Sienna Miller and the age of agelessness. Post continues after video.

This is about the fact that only a few short years ago, and certainly a decade ago, this is NOT how women's 40s looked.

This image says that Miller, literally glowing with conventional beauty and visible health, is a symbol of how age is becoming increasingly irrelevant when it comes to life stage, lifestyle, and choices.

It's a sign that we are inching towards an era of agelessness. Erasing age standards, even as we re-embrace beauty ones. Youth being the most enduring among them.

Here's a tiny sign of age-erasure's success: When I was training as a journalist, including a subject's age in their first mention in any article was standard, essential. Here's that Holly Wainwright, 53.

Now, including that detail in a story about anything other than age feels like an affront.

An example of how many publications now only mention age "when relevant" would be in the coverage of an event like the Australian Prime Minister's wedding to Jodie Haydon.

In a recent lengthy profile of Haydon The Sydney Morning Herald did not reference her age once. Nor does it appear in any of the Herald's reporting of the wedding. The only ages mentioned are those of Albo's son, Nathan, 25. And Jodie's niece, flower girl Ella, who is five.

See, "when relevant".

This feels like significant progress from a time where a woman marrying in her 40s was worthy of note, speculation and stereotype. And it feels like a recognition of how ageism disproportionally affects women. Because the unpicking of women's lives from the decade they're in has always been complicated by biology. Are they of child-bearing years, or not? And if not, what are women for, exactly? That's how it can feel, to have your age listed, always, as a way of thin-slicing you and your worth.

Ask any woman over the age of 45. Her age will be part of her story in a way it just hasn't been for men.

And yet, here I am, with my Sienna Miller obsession. Why?

Well, because it's new.

Image: Getty.

"Life begins at 40" might have been a slogan on greeting cards for decades, but our culture never believed that. Women over 40 were on a downward trajectory, in all kinds of ways. Not least, in their vitality and attractiveness.

This is a popular image doing the rounds at the moment. It's an ad, from early 1971, for a nutrition subject called Geriton.

Its point is that all the women in this ad are meant to be one age - 47:

This add is from 1971. These women are all 47 years old.

Four years older than Miller. Two years older than another actress who's been a poster-child for agelessness this year - Kristen Bell.

Bell's age has been blurred for different reasons. In the enormously popular rom-com Nobody Wants This, nobody mentions age, either. Even as the characters are dating and getting engaged, talking about babies and wanting them and not wanting them. It just never comes up. The only rush Bell's character Joanne will admit to in getting Noah to commit is about beating her sister up the ailse.

And this too is progress. Literally.

Image: Netflix.

Technological progress of all kinds - in skincare and cosmetic surgeries, in ever-advancing information about health and exercise and fertility treatments, in hormone replacements, in the constant bio-hacking revelations of the "longevity industry" - means we know how to look younger and seem younger, and live life like we're younger, for longer.

The women in that Geriton ad - 47? We don't think so. In a retelling of that image for 2025, there will be Botox and nose-rings and c*nty little bobs and barrel-leg jeans and yes, maybe even a baby bump.

In popular culture, 40s used to be OLD. Fifties used to be ANCIENT. Beyond that was just unthinkable.

But now? Well now if major life-goals, like parenthood, are achieved in someone's 20s, we're suspicious. Why the hurry?

We exist in a time when some of the world's richest men are declaring that they might not have to die at all. And we have one of the most famous 70-year-olds in the world - Kris Jenner - stitching on a new face and sharing her surgeon's details.

If a woman has wrinkles, or grey hair, or anything other than an acceptably straight-sized, midlife body, the question is asked: but why don't you… fix that? You know you can fix that, right?

We have extended youth by a couple of decades, and we have redrawn the rules for what the 'middle' part of life looks like. The era of agelessness, where ageing is a choice.

At least, for some of us.

Listen to this MID episode. Post continues after podcast.

Face lifts, bio-hacking and cutting edge fertility technology are, of course, hallmarks of a particular class. Your access to it, your resources to pay for it, your willingness to undergo blood spinning and supplement chugging, genetic testing and hyper-restricted eating programs - it all feels, at this point, like science fiction for the one per cent.

But it's coming. The longevity industry is worth an estimated $21billion and projected to triple in the next decade.

The wellness industry at large, with its broad promises of us all living better for longer, is worth $2trillion.

And remember, once, Botox was something only the A-list did. Now you can get it at your suburban hairdresser. It's one of the most effective trickle-downs in history.

So, back to Sienna Miller.

The broad reporting of Miller's pregnancy is not focused on her age. Not in a way it would have been even half a decade ago. It's just not that interesting or uncommon any more.

We are all more fixated on the outfit than the numbers. Fluffy platform mules?

We are not even really that surprised at how young Miller looks, because all the famous 40-somethings look like that.

None of it is worthy of commentary, which is the point. The Culture has successfully rebranded our 40s, and extended youth.

Whether our insides truly match our outsides is still a question. When I was a 40ish woman having a baby, the word I was frequently hearing was "geriatric". That a post-35 pregnancy is classified that way seemed ridiculous to my ears at the time.

Imagine how outlandish it seems applied to Sienna Miller.

Feature Image: Getty.