There's a name for this: 'gotcha' pregnancies and Kate Spicer, the writer in this picture, admits she's played the accidentally-on-purpose game and as a childless woman in her thirties, would be delighted to fall pregnant under any circumstances. She writes honestly:

Three weeks ago, I bought a pregnancy test. As a single, childless woman in my late 30s, my exact thoughts while I was waiting for the result were as follows: 'If I am not pregnant, then good. I'm happy.

Life continues as before. Panic over. If I am pregnant, then that's terrifying. But thrilling, too. A happy accident that was meant to happen, whether I stay with the father or not.'

The test, as it happened, was negative which means, for me, another narrow escape or a lost opportunity – depending on which way you look at it. 

That's not to say I'm on a crazed mission to get pregnant. I am now 39, but I have felt broody on and off throughout my 20s and 30s. And so, when I'm in a relationship – and sometimes even when I'm not – I have long taken an incredibly casual approach to contraception; waiting, I think not even that subconsciously, for the happy accident to happen to me.

Yes, I know about the dangers of sexually transmitted diseases, and I know the emotional damage casual sex can leave in its wake. I'm not some reckless evangelist for promiscuity.

People have a lot of sex for pleasure these days, but there has to be a purpose to it at some point. So I have always thought: 'You know what, if I do get pregnant, I don't mind. It's not the end of the world. It's like I'm letting nature decide when the time is right.

So far, the time has not been right, and thank God for nature's motherly wisdom. But if it were to happen, it would not be a disaster. That's why I wouldn't chastise anyone – man or woman – who sought out parenthood on a totally subconscious level.

So few relationships are perfect these days. We do not live in a society where everything is neat and tidy any more. Sometimes, desperate measures are called for if you want to get pregnant. And, if the woman has any sense, one hopes she will have chosen someone who is going to deal with the consequences in an adult way.

I haven't used contraception for years and years – I hate taking the Pill – and I'm always entirely honest about that with the men I sleep with. As far as I'm concerned, if a guy is having unprotected sex with me, then he knows what he is doing, and if he doesn't, then he is just arrogant and more fool him.

I don't just sleep with anyone. To even have sex, let alone unprotected sex, in the first place means the guy must have something special. I don't want an accident to happen with just anyone. They've got to have good genes even if they are not relationship material, and I'm sure that is always secretly at the back of my mind each time I fall for someone. It's a biological thing; I'm subconsciously on the lookout for good breeding stock.

Perhaps I should be more calculating. I remember a close female relation of mine, very proper and upper middle class, telling me she was going to have sex just to get pregnant. Any man would do.

But I have never wanted to do that. A happy accident is one thing, but actually to go out and plan an 'unwanted pregnancy' is something else entirely, and it's not for me.

Men can want to be fathers accidentally on purpose, too, you know. I don't think they are always the poor victimised man with some awful harridan forcing her fertility wishes on him. Men are equal players in this game.

I know men who have been caught out by one-night stands or by relationships that weren't going anywhere. They might think their lives have been screwed up, but they always love the child. So is it really that bad?

On the few occasions I've had scares/thrills, most guys were, with varying degrees, cool to very excited about it, despite the fact we had never seriously talked about having kids.

When I think about it rationally, though, if I had been pregnant any of these times, it would have been far from ideal. I have no doubt that I would have loved the baby unconditionally. But I doubt very much that I was ever mature enough to settle into a long-term relationship with any of the men I took risks with.

And as the child myself of a marriage that ended in bitter divorce, I don't really want to impose a broken family on another. Or, worse, no family at all. There are many very harried and lonely single mothers out there, and I count many of them among my friends. Their struggle is not to be underestimated.

Marriage is no guarantee, of course. I've got a really good friend who was very happily married. She had the big house in the Home Counties and children at private school. But then her husband left her, skipped the country and now she's a penniless single mother, so even the safest bet can let you down.

I suppose what I'm saying is that there are no guarantees. Given the fragility of the nuclear family dream, are women really so bad for just procreating as and when an opportunity arises?

Of course, a part of me does feel sad that I haven't met a person with whom I want to raise children. But that doesn't mean I don't still want children. I've watched with a benign envy as my brother and sister-in-law start their family.

So while there's still time, I will probably keep on playing this particular game of fertility roulette. I just can't help myself.

On this subject, there's a new book called Accidentally On Purpose which has been written by 39 year-old Mary Pols (below) who DID fall pregnant after unprotected sex on a one-night stand. The book is about ''…her emotional journey to single mumdom, not to mention her heroic attempts to forge some sort of relationship with the stranger who fathered her child.'