I went to live in New York when I was about 32, a time in my life when I was single. It wasn’t the kind of single of my 20s, which I’d loved; it was “single with anxiety attached”.

Rising above the traffic noise of the flat I was renting (corner of 23rd and 9th, first floor, about 16 foot away from the endless honking of NYC’s truck drivers) was the ticking of my body clock. It was a totally unknown feeling. I’d been a maternal child (or so my mum tells me – she also thinks I was good at lacrosse, so have a pinch of salt handy), but I’d embraced my adult freedoms and loved every second of my child-free 20s.

I hadn’t had a yearning for a child. And then I did. I really did. I’m not alone in this hormonal fluctuation. And in NYC I was not alone in feeling alone. Don’t worry, I’m stopping there with the alone thing.

As any fan of Sex and the City will know, Manhattan is as famous for its lack of suitable men as it is for its yellow cabs. Someone once told me that there are five single women for every available man – so it’s pretty obvious that not everyone who wants to settle down and start a family finds it easy to do so.

Manhattan is also a place that thrives on the marketplace. If there’s even the merest whiff of a demand for something, then a supply will soon emerge, and so from the shadows crept a new form of fertility treatment – not new to the medical profession but new to the external market – egg freezing, or oocyte cryopreservation, if you want to be technical about it.

It does what it says: it’s a process whereby fresh eggs are harvested from a woman’s ovaries, frozen, and later can be thawed, IVF-ed (a nontech term) and reimplanted, in the hope that a normal embryo will grow into a healthy baby.

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Even in 2004 the process was really the prerogative of those facing cancer or life-changing conditions or circumstances. But I remember seeing the very occasional ad for it in US women’s magazines and there was a hint of it in conversations with other 32-year-old single Manhattan women.

So I phoned a few clinics and asked lots of questions, probably too many because receptionists got fed up and lost their Manhattan poise. My questions were simple, though. How successful was egg freezing? How many babies had actually been born through it? Who did the freezing? Who checked the temperature? Where were the eggs stored? What happened if there was a power-cut? What if I waited until I was 50 – was that too old to use them? In the end it all seemed just a bit too uncertain.

I went on loads of dates instead. And Dear Reader, my life changed. I now have two children – they’re 11 and eight – and I’m eternally grateful for them. I had my son when I was 36 and my daughter at 39. But I remain intrigued by this offer of the chance to “change your fertility destiny”, as one of NYC’s leading fertility clinics suggests in its ads.

And now it’s no longer in the shadows. Those giants of Silicon Valley (the Googles and Facebooks) are providing it for their female employees in their corporate healthcare packages. This creates a new dawn for the treatment – not just because it makes it available to thousands more women, but also because it rubber-stamps it as a procedure.

For some, those questions about safety and outcomes are answered by the simple fact that these mega-companies are approving it.  I agree that egg freezing seems liberating and, as one woman I spoke to for our programme said, it provides “relief and opportunity”.

If your anxiety about never becoming a mother is overwhelming, if you simply want to do well in your job for a few years, this would seem a solution. On the other hand, is it also these companies saying, “Give us your best years and put those family ambitions on ice”? Literally. And does it sort any of the things that prevent women from pursuing the same career timelines as men?

Wouldn’t it be better to provide workplace creches, non-judgemental paternity leave, job security for a woman – the kind where she knows that she returns to work without an imaginary Post-it note on her back saying, “Part timer, bound to be thinking about baby wipes not work”?

And it is the promise of the whole thing that still troubles me. It’s almost impossible to find your way through the data. The Human Fertilisation and Embyrology Authority, which is the UK’s regulatory licensing body, says, “Success rates are still low – an average of eight babies born per year between 2008 and 2013 (in the UK).”

If you’re in your late 30s, those outcomes are even harsher because your eggs are older, your uterus is older, you are older. Doctors may well be able to say that thousands of babies are being born around the world as a result of egg freezing – and some do say this – but break down the reasons for freezing, even the different processes used, and that might well be misleadingly optimistic.

It’s such a mighty, mighty promise this oocyte cryopreservation – the promise of a fulfilled life for some. One doctor we spoke to said it ranked up there with the arrival of the contraceptive pill in the world of women’s fertility. If she’s right, then we need more facts, more investigation and way more discussion. I don’t think we have any of those things quite yet.  

The Great Egg Freeze is on Monday 11.00am Radio 4