Three months into a fledgling relationship, divorcee Dan Short was in bed with his attractive, much younger partner when she whispered a proposal that punctured the mood.

It wasn’t so much an actual demand as a loaded question that had Dan reconsidering the future — not only with her, but about his life in general. Yes, the 50-year-old father-of-two was besotted — ‘I was punching well above my weight,’ he admits — but one thing was entirely out of the question: more children.

So when, in the heat of the moment, his 30-something girlfriend asked whether they should use contraception or not, he found himself in a quandry that was later to result in rather drastic action.

‘There was such a big question mark at the end of the sentence,’ recalls Dan. ‘I didn’t doubt she’d make a fantastic mother, but that wasn’t what I wanted.’

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Dan Short, 50, Steve McLaren, 41, and Martin Thomas, 42, pictured left to right, have all had a vasectomy to avoid having more children. The trend is increasing among men aged 41-45

While the couple did use contraception that night, things fizzled out weeks later.

Dan says: ‘It wasn’t a coincidence that I went on to have a vasectomy shortly afterwards’. As dramatic a reaction as that may seem, Dan still maintains it’s a prudent course of action, not just for himself, but for other divorced dads dating childless younger women.

He explains: ‘On numerous occasions during my single life, women have casually asked about contraception.

‘You do have to be careful because these are the ones looking for a man to father their children. And they can be ruthless in their pursuit of that.’

Is this the bravado of a deluded middle-aged man? Or the uncomfortable truth about dating as a divorced, evidently fertile male?

As a psychotherapist with 20 years of experience in couple counselling, I have discovered Dan is far from the only middle-aged divorced father choosing a vasectomy to safeguard his return to the dating market — to the extent that a recent survey found the most common age range for men undergoing the procedure is 41 to 45.

There are several factors behind this — the high rate of marital breakdown, men fearful of being ‘tricked’ and single women in their 30s and now even 40s suddenly experiencing the all-encompassing desire to become mothers. In some cases they are becoming increasingly predatory about seeking ‘father material’.

Dan Short (pictured), 50, underwent his vasectomy at the age of 43

Although convinced they didn’t want children while they built their careers, suddenly — bam! — their biological clock starts ticking. It really can happen overnight. They will do anything and everything to pursue this, even if it means duping a man into having unprotected sex.

Their targets, meanwhile, fear getting trapped in the wrong relationship, but also dread the financial implications of a new baby. After all, research suggests you’ll shell out as much as £230,000 caring for a child before he or she reaches 18: the figure doubles if you add in a private education.

If you don’t have the wealth of ageing celebrities such as Ronnie Wood or Rod Stewart, who have gone on to have second and even third families, then the impact on your life is going to be enormous.

As for whether taking such extreme action is merely wishful thinking, Dan claims that although it sounds ‘arrogant’, dating younger women ‘is very easy for men like me’. Combined with the fact that a man’s fertility is unending, this makes him vulnerable — so he needs to be continually responsible about sex.

That’s why Dan from Hastings underwent his vasectomy in 2010 at the age of 43. He says: ‘While it was an NHS procedure, it was performed at a private clinic. It was very professional: I was in and out fairly quickly one lunchtime without any complication afterwards either. Totally worth it for peace of mind.’

Dan, who works in the film industry, split up with the mother of his two sons in 2004, having been together 17 years.

‘Fortunately, at first, I had a serious relationship for four years with someone who didn’t want children,’ he says. ‘I then had a one-year relationship before embarking on a couple of short-term ones.

‘The women were typically in their 30s. If it looked as though we were going to sleep together, I always addressed the issue of children head on, explaining that my days of playing football every weekend with a toddler were long over.’

Dan recalls a number of awkward situations with those interested in more than an amorous affair: ‘But I’m someone who is very careful. I’ve never had unprotected sex.’

Currently single, he says: ‘I’m not looking for a relationship: I’ve just started a new job and my life is hectic already. If I want to unwind, I’ll pop along to my local pub for a pint with some friends.

‘I’ve done the small children phase of my life and it isn’t something I’d want to do again. It has upset some women and I appreciate that I’m being somewhat selfish.’

Steve McLaren (pictured), 41, had his vasectomy last autumn and says that he had wanted to have one since he was 33 but waited for his wife's sake

But, more than that, he insists he’s being responsible and loyal to his existing children.

‘I have two fantastic sons who are grown up now. I have a great relationship with them,’ he explains. ‘I can’t imagine how they’d react if I told them that a little brother or a sister was on the way.’

It’s another reason why, over the past seven years, Dan is confident he ‘hasn’t regretted the vasectomy once’.

Steve McLaren, a 41-year-old physiotherapist from Newcastle, who describes modern dating tactics as ‘terrifying’, is another man without regrets about taking back control.

Martin Thomas (pictured), 42, had to wait seven years to be approved for a vasectomy

After his marriage collapsed in 2015, Steve tried dating sites such as Plenty Of Fish and Tinder only to be astonished at how brazen some women were about wanting a baby.

‘Even if you put on your dating profile “no” to the question: “Would you consider having children?” it is still the first question some women ask.

‘I recall thinking, “Whoa, steady on, we don’t even know each other yet!” But then if you are desperate to have kids, I suppose you just want to get on with it.

‘The whole experience was a bit terrifying, if I’m honest. There is a sense they’re hunting for Mr Right Now and that they need to “cram in” having a baby before it’s too late. There is no subtly about it whatsoever.’

So Steve had a vasectomy in autumn 2016 — something he’d wanted to do since the birth of his second child, Martha, now eight. He was so adamant that she and her brother Jimmy, 11, were enough for him that he even secretly consulted his GP about a vasectomy while he was still married.

‘When my then wife found out about it, she got very upset I’d even consider it without consulting her. She thought we were too young to make such a final decision on our family — I was 33 — so I reluctantly put it on hold.’

But when Steve’s marriage broke down two years ago, after 20 years together, his fertility played even more heavily on his mind. ‘The guilt I felt about the collapse of the family was awful, it was one of the worst experiences of my life.

‘Adding more children into the mix would reduce the time my son and daughter would have with me. It wouldn’t be fair on them. As soon as we separated, I started thinking about going ahead and getting a vasectomy done.

‘It wasn’t because I was seeing someone at the time, either. I very definitely didn’t want to be put in the position, whether I was in a serious relationship or not, of the person I was with having an accident and getting pregnant.’

While it hurt, there have been no lasting medical issues. Thankfully the person he began seeing shortly afterwards reacted ‘perfectly well’ to it. He explains: ‘I told her it was done and dusted. There was no discussion about it. Fortunately she already has children and didn’t want any more either.

‘Fatherhood is a life-changing experience, but there is no way I will be doing it again.’

With more women waiting until over the age of 30 to have children, men are seeking to protect themselves rather than trusting that their partner is using contraception (file image)

But for others who are considering following Dan and Steve’s lead, Martin Thomas, 42, now married for a second time, has a word of warning. Having divorced his first wife at 30, it was seven years before his doctor would consent to him having a vasectomy.

He says: ‘I’d gone to see my GP as soon as my marriage ended. I explained the situation I was in, that I was no longer with my ex-wife and that I saw my family complete with my son and daughter. I said it to him again and again that I didn’t want any more children. Even so, I was met with disbelief. My doctor somehow managed to talk me out of getting the procedure done, saying I was too young and I might change my mind.’

And it seems there was some truth in this prediction.

Meanwhile, Martin spent his return to the dating game as a divorcee feeling ‘scared to death’ of being lied to by women about taking the Pill.

He dated ‘lots of girls’, reasoning that because he’d spent years elbow deep in domesticity, this was his chance to enjoy those lost years. Yet his delight at this new-found freedom was marred by the dread of unwanted pregnancy.

He says: ‘I’d describe myself as a serial monogamist.

‘I had two relationships which each lasted a year. Neither woman had children, and even though I’d tried to ensure we were on the same page regarding not starting a family, I had sleepless nights about getting the text or call telling me I was going to be a father again.

Martin met his second wife one year after his vasectomy and at times questions if he made the right decision to have it when watching her struggle to accept they can't have kids (file image)

‘I had a lot on my plate: I was running a painting and decorating business, renovating my home and I had the children to stay regularly too. But women in their 30s, if they aren’t mothers, are at a dangerous age for men like me. Even if they insist they don’t want children. I was terrified of ending up a father again.’

Martin began to worry about having to take a woman’s word when she said she was taking contraception: ‘There was never any particular incident, just those anxious feelings of knowing your future was resting in someone else’s hands. I was always very vocal about this too.

‘While women always tell you what you want to hear, every man knows of another chap who has received the dreaded, “Darling, I don’t know how it’s happened, but guess what? We’re having a baby!” call.

‘I wanted to be able to enjoy the intimate company of women, but without the worry of getting that one message that most guys in my situation dread.’

Eventually, in 2011, Martin, who lives in Bridlington, Yorkshire, plucked up the courage to insist on the procedure and his doctor finally agreed. Ironically, however, a year later he met and fell in love with his now wife, Kimberley, 36, a full-time mum to two children from a previous relationship.

‘Kimberley would have loved to have had more children with me. She was extremely upset when I explained to her what I’d had done. It did make me question whether I’d done the right thing.

‘Even today she still loves to brood over what our children would be called or what they would look like.’

While many may feel Kimberley’s pain, I would urge acceptance on her part. Having a child against the father’s will is, unsurprisingly, likely to break a relationship.

Grappling over when or who to have children with is a very modern problem that isn’t going to be resolved any time soon. With almost one in two marriages breaking down and the average woman giving birth over the age of 30, it’s no surprise to me that more and more men are taking precautions — however drastic.

My advice to either party facing this dilemma is to be honest. If you can’t agree on the desire to have a family, it is best to walk away with your integrity — if not your own fertility — intact.

Boundaries: How to Draw the Line in Your Head, Heart and Home, by Jennie Miller and Victoria Lambert out January 11 2018. For more information visit jenniemillercounselling.co.uk