I took the call about 5am. I was expecting it: I had gone to bed the night before cradling my mobile. Into the dark dawn of my north London bedroom came my brother's voice from Canberra. It had a strange, soft tone in it that I had never heard before.
It's a girl, he said. I was a godmother and an aunt.
The first time I met her - this charge, this person for whom I had some undefined responsibility - she was about six months old, already sporting the prodigious belly for which she had become famous in the family circle.
It was impossible for me not to love her immediately, and fiercely. But she eyed me with great suspicion, less than pleased with the sudden appearance of an imposter, particularly one on such affectionate terms with the grandmother whose attention she had hitherto dominated.
But we became friends pretty quickly after that. My relationship, with her, and her equally brilliant little brother, is based on a mutual love of buffoonery, and the fact that I will feed them successive ice-creams until they stop asking.
We also trampoline a lot. With or without a trampoline, they are the only people I know who literally jump with excitement when I visit.
My niece starts school in a few weeks' time. The belly has given way to a less babyish figure (we mourn the belly), and the Gypsy bride fairy dresses will have to become a weekend-only thing.
Things are going to get more complicated, and my duties as an aunt will evolve. At some point she will grow tired of the kissing monster game but she will need me in more practical ways.
The psychologist Steve Biddulph, author of the hugely popular Raising Boys, says that teenage girls are facing a ''catastrophe'' of mental health problems unknown to previous generations.
He has called for an army of aunties to rise up and stand staunch beside their nieces as they face the onslaught of adolescence.
Biddulph believes teenage girls have never been more unhappy, stressed and anxious.
They are bombarded with media images that not only tell them that hotness is more important than cleverness, kindness or even coolness, but define for them exactly what hotness looks like.
Hotness looks like a $25 boulevard prostitute and takes many of its cues from porn culture.
Girls are sexualised early and subjected to greater scrutiny, thanks to the unrelenting panopticon of social media.
The kinds of things my generation would have consigned to their girlish diaries are now blurted out to a gallery of peers on Facebook, and those peers can be very cruel.
Just when a girl's identity and her sense of self is at its most fragile, she is facing more potential rejection and judgment than the most robust of egos could handle.
''We have to love them better, make them stronger, and get the corporate world off their backs,'' Biddulph advises. ''We have to stop the trashing of girlhood.''
This is where the aunty army can mobilise. Aunties, he believes, can fill some of the gaps that mothers cannot. Mothers provide unconditional love, stability, routine and regularity. But as anyone who has ever been within eye-rolling distance of a teenage girl knows, they can't always be their daughters' confidantes.
Biddulph believes that girls' fathers set them up self-esteem-wise, and their relationship with their dad is a good predictor of how they will later relate to men romantically.
But good aunts are the key to girls becoming ''savvy and self-believing'', he says.
Aunts are the ones who, after their mothers, can be role models of self-reliance and self-acceptance; who can provide an example of how to live confidently without taking life too seriously.
Mothers juggling careers and multiple children need all the help they can get, and delayed motherhood means there are plenty of maiden aunts about, although in the post-Austen era they are more likely to be into kite-surfing or a Master of business administration than needlepoint.
Marketers have already picked up on this. As reported by Fairfax Media before Christmas, the new breed of aunt has even been given an acronym, PANK, which stands for Professional Aunt No Kids.
PANKs, say the American public relations people who dreamt them up, spend a lot of money on ''gifts and experiences'' for their nieces and nephews, and hence are worth marketing to.
A report by these American marketers says that one in five American women is a PANK, with a median age of 36. They spent an average of $385 on each child in the past year and more than 75 per cent spent $500 per child.
The figures seem pretty accurate to me, but I dislike the idea of marketers getting their grubby hands on my aunty-hood. This is the same breed of people who hit on the lucrative ''tween'' market and have been selling sexualised rubbish to girls ever since.
An aunt's responsibilities are relatively modest - I'm pretty sure all we are contractually obliged to do is return the children in one piece - and consequently it is a relationship that can be entirely based on fun.
The aunty army should be concerned with providing experiences, adventure and escape. Aunts have not always been well portrayed in history. We're spinsterish and frumpish, sometimes mad and often drunken. Maybe we're still all those things, but maybe we can also help.