by KATE MULVEY, Daily Mail

As I lay on the bathroom floor, clutching my stomach, the tears rolling down my cheeks like torrents, all I could feel was a gaping, infinite sense of loss. Yet I was not at some funeral of a loved one, I was at a child's fourth birthday party, and I was the only woman there without a baby.

I never planned on being 39 and childless but somehow, here I was, a few months shy of my 40th birthday and all I was clutching was a Prada handbag.

Back at the party, the yummy mummies were settled around the kitchen table as they casually fed their toddlers pizza and wiped up baby sick from their newborns. Amid the mayhem I was shouting into my mobile and organising my glamorous Saturday night ahead.

I laughed and joked about how I would be wearing fluorescent pink hot pants at a party, but it was empty laughter.

My nephew came over and sat on my knee. He flung his arms around my neck and clung to me. I could smell that unique baby smell and marvelled at the sensations in my body as I held him close.

Yet I knew that I would have to hand this little bundle back and then all I would feel would be the aching loss for the children I will never have.

Grief and loss. These are two emotions that have become commonplace in my emotional repertoire of late. It can be frightening to yearn for a child, and it is hard to fathom the desperate urgency that comes with thinking that maybe, one day, I could be a mother.

But after that party, I had an epiphany. In six months' time I will be 40, and after a great deal of soul searching, I have decided that I am bowing out gracefully from the baby race. I cried myself to sleep for weeks. No child. Not now. Not ever.

People look at someone like me - a woman who is still attractive, has her own career and doesn't have children - and think that either I am an unfeeling monster or a tragic failure. Sometimes they say it to my face.

Just last week, a well-meaning friend stood triumphant with her twoyearold on her hip and told me: "Well, Kate, you don't like children do you?"

I lost my rag. I made it clear that I hadn't made a choice not to have children. I am not one of those women who sat down at 30 and categorically factored out babies from their life plan. I love children and share all the motherly instincts of most women.

But it is a painful modern truth that there is a growing number of women - the proportion of women under 50 without children has doubled over the past two decades - who have simply forgotten to have a baby.

Somehow, amid the schmoozing and the broadening of the mind, the baby question has always been put on the back burner.

And then suddenly - at exactly the point when infertility cannot be ignored - I, like other childless women, realise it is probably too late.

What went wrong? How is it that the age-old business of having babies has suddenly become fraught with so many difficulties.

An important clue can be found back in the late 1970s when I was in my teens. I was part of the generation of schoolgirls who, instead of being propelled towards childbirth by cultural and religious expectations, could balance motherhood against a career and good times.

The result is that my childless contemporaries and I are the fallout generation from the sexual revolution, the real-life Bridget Jones's who spend their evenings getting drunk instead of reading bedtime stories.

We were told we could have it all, but in reality we were sold a pipe dream. The reality is that we forgot that we are helpless in the face of our biological clocks. And now it is simply too late for a lot of us.

Back then it all seemed so different. We were being "freed from a life of drudgery" - or so the feminists ranted as they deconstructed the romantic ideal of marriage and motherhood. And along with the rest of the neo-dolly birds, I burnt my M&S bra in the name of freedom.

The very act of having and rearing children was seen as counterintuitive; boring and inconsequential at best, ruinous to any self-development at worst. My friends and I embraced the feminist ideology that was going to give us a life of glittering prizes.

At the time our narrow notion of self-development saw settling down as a sacrifice too hard to pay. We wanted the same chances to succeed as any man and we wanted the same choices that they had.

Flashback to my early 20s and I was living that promised life. I was at university in Kent, studying Italian, and life was a round of parties here and abroad. My dating diary was full of London's eligible bachelors and my friends were as footloose and fancyfree as I was.

There was a whole gang of us who used to hang around the Roebuck and other pubs in Knightsbridge, always ready for a party or a trip to the Embassy nightclub.

When a friend of mine got married - at the age of 25 - we pitied her, got trashed on vodka and were sick in her parents' bedroom. We were living the lives that only men had been allowed to live. We drank too much, smoked too much, ate badly and behaved even worse.

We were the modern women who didn't care less about oiling the wheels of the middle-class dinner party, much less about getting a mortgage and having 2.4 children.

I was living the glossy magazine lifestyle that was built around freedom and choice.

After university I worked in the fashion industry and then travelled in Europe, making the most of my fluent French and Italian while enjoying a life of parties, late nights and fun.

I had the freedom to drink wine into the small hours, instead of going to bed early ready for the school run; the freedom to book a holiday for one; and the freedom to spend my money on myself.

Then, when I was 33, my elder sister gave birth to her first child at the age of 38. When I went inside the delivery room and saw her husband burst into tears of joy, I realised in that instant what real happiness meant. It was a feeling I had never experienced.

So what did I do? Instead of working up to a reality shock about my own ticking body clock, all I remember thinking was how lucky I was that my gym-toned body wouldn't be ruined by stretch marks and sagging breasts.

In fact, even though I knew deep down that they had got their life choices right, part of me pitied my sister and the other new parents as they tried to come to terms with the shock of how having a baby had changed their lives. After all, weren't their faces etched with weariness?

One day I went round to see a friend who was recently divorced after her husband left her shortly after she had given birth to their third child. She was a wreck and so unhappy that she took her bad mood out on her offspring.

That evening, as I watched her put her children to bed, I almost ran out of the house, heaving a sigh of relief as I went, reassuring myself how clever I was to have escaped such a terrible fate.

But now look at me - and look at her. She has three lovely teenagers, who are all at top London schools and who all give a powerful meaning to her life. All I have are the empty hours to fill at the weekend.

Don't get me wrong - I'm not blaming anyone else and I certainly don't expect any sympathy. I realise now that you get out of life what you put into it.

Besides, there have been so many times when I could have jumped on the baby wagon myself.

When I was 35 and living in Geneva with my Swiss boyfriend, he broached the subject of children. He had a well-paid job while I was a freelance writer and had the time to have a baby.

It should have been perfect. But all I could see was years of mundane drudgery looming ahead and boring children who I would never be able to "switch off". So I left and went back to London, to a pokey flat in Earl's Court.

Two years later, I published my second book. I was 37 and friends were beginning to view me as a bit of a shallow hedonist. Suddenly, I wasn't a glamorous singleton any more; I was just a bit sad.

They were too preoccupied with taking their toddlers to ballet classes to live vicariously through my romantic adventures. The truth was, I was slowly becoming a sad non-person in the world of child rearing and it was painful.

I made more of an effort but, as I accompanied them and their children to the park on a Saturday afternoon and shivered in the cold, I felt like a failure.

I had no little nose to wipe, no tears to dry or words of tenderness when they fell down. All I had was a hair appointment.

Looking back, I think I was suffering from delayed maturity syndrome. I was so used to acting like I was 27 that I had convinced myself I was in the prime of my life.

The trouble is no matter how much botox we inject into our faces or how many miles we run on the treadmill, we cannot change our biological reality.

Delayed maturity means that many women out there waste their narrow window of fertility. Right up until last year I was in denial, telling people that I was a "free spirit" as if it were some kind of badge of honour.

Then last summer my little sister, who had hit 35, had her second boy and my desire to have a baby hit me like a lorry. I found it excruciatingly painful to be around my new nephew Oscar and stopped seeing both my sisters for over a year.

One of the few times I held Oscar - we were at a friend's christening - the physical craving to hold my own baby was unbearable.

The experience really shook me, and I was forced to recognise for the first time in my life that babies are a big deal and that I have missed out on something so fundamental to my happiness.

And recognising that fact is no comfort; the hole is simply too big. Even months later the emotions are so raw and close to the surface. The pain of wanting a child never goes away.

Whenever I am out my eyes are drawn to babies. I feel a terrible urge to pick them up and hold their tiny bodies. I sit and watch toddlers in playgrounds and listen to their peels of laughter ring in my ears and don't know whether I want to laugh or cry.

So why, when my life seems so bereft without children, have I given up on motherhood?

I have to say, I went through a period last year when my baby yearning was so intense that I said to myself that if I didn't have a man by the time I was 40, I would either ask an obliging male friend or find a sperm donor.

Now I realise that, for me, marriage and children are a package.

I am single. Even if I met Prince Charming tomorrow, we would still have to date, marry and then have the children. I would be a wrinkly 44-year-old before I even had the epidural.

As desperate as I am for a child, single motherhood is also not an option. I have seen friends go through it and it is brutally hard. The loneliness of raising a child alone is too much.

Besides, being a firsttime mother in her fourth decade does not come with much dignity. Who wants to be the oldest mother at the school gates?

Having a child after 40 is a bit like saying you want to run a marathon at 65 and the odds are stacked highly against you. For a start, 50 per cent of pregnancies in women over the age of 40 end in miscarriage.

I am not pretending that the awful truth has not gone away. I live with my decision every day.

But a baby is not a prize that you have to win at all costs. And I think the costs are too high for the baby to pay when the mother is over 40.

The last thing I want is to carry on working and raise a latch-key kid. A lot of my friends and acquaintances are rearing an army of neglected middle-class children.

They are women who, in order to maintain the lifestyles they want, keep going out to work, leaving their children to pay the price as they need to be cared for outside the family. Even Madonna and Cherie Blair, with all their money and helpers, are busy career women, snatching quality time with their children.

On the plus side, now that I have finally put the baby question to rest, I am finding that there are benefits to having a life free of offspring.

There is the freedom to do what you want and to pursue the career that you want. I am also newly in demand with older, divorced alpha-males.

Having done the family and success thing, they are not interested in having another family and find a younger woman unhindered by her own children an attractive companion.

The emotional progression I have been through in deciding not to have children is just like going through a bereavement.

As a friend who lost her mother ten years ago put it, the pain is still raw, but it just becomes a part of your life and you learn to deal with it. It is when an emotion is fresh that it's scary.

So, for me, I am slowly discovering that while the suffering will not go away, there is a way to live with the wounds.