Father time?

GORDON Brown, Ken Livingstone, John Humphrys, Des O'Connor, Mick Jagger, Rupert Murdoch, Charlie Chaplin … an oddly assorted bunch, surely, but what they have in common is that all fathered children when well into their fifties – or much later, as in the cases of O'Connor, Murdoch and Chaplin, who sired offspring when they were in their seventies. Society has tended to focus on a woman's countdown to the menopause and her end to childbearing, while presuming, in a slightly nudge-nudge manner, the apparent ability of men to father children until they are overtaken by mortality, if not by child-maintenance orders.

The world's oldest recorded father, after all, was the late Les Colley, an Australian mine worker who in 1992 was almost 93 when he fathered a son by his Fijian wife. Recent UK statistics suggest that more than one in ten of all children born in this country were to fathers aged over 40, more than 6,000 of them to those aged 50 or more.

Last weekend, however, French scientists made clear what some had already suspected but no-one had actually spelled out – that it is not just women who must keep an eye on their biological timepieces when it comes to procreation. A study by the Eylau Centre for Assisted Reproduction in Paris suggests that chances of a successful pregnancy start dropping when the father is over 35, and become significantly lower when he is over 40.

In the survey, involving more than 12,200 couples undergoing fertility treatment, the scientists found that miscarriage rates increased significantly and both natural and assisted conception became more difficult if the father was over 40. The findings were announced to the European Society of Human Reproduction and Embryology when Dr Stephanie Belloc, the study leader, stressed that they had important implications for couples wanting to start families, and added that such couples should be offered in vitro fertilisation (IVF) treatment to help achieve successful pregnancies.

It was the first time such a strong correlation between the age of the father and reproductive success had been identified, Dr Belloc told the conference. "Until now, gynaecologists have focused on maternal age and the message was to get pregnant before the age of 35 or 38, but now the gynaecologists must also focus on paternal age and give this information to the couple."

Laurence Shaw, a consultant in reproductive medicine, regards the news as a very important issue, "and it's great that it's making headlines". A deputy medical director of London's Bridge Centre for fertility, gynaecology and genetics, Shaw was at the Barcelona gathering when the report was announced. "We have been obsessed with the fact that women's reproductive capacity declines at a rate faster than that expected for ageing alone," he says. "This study shows us what we sort of knew but weren't paying much attention to … that a man's fertility declines as well. This is ageing."

But Shaw highlights another issue related to the findings which doesn't yet seem to have made the headlines. While women who become pregnant at 40 tend to worry about possible problems such as Down's syndrome, as their chromosomes deteriorate with age, "what we guys don't seem to realise that our Y-chromosomes are deteriorating as well. Maybe our facility is just declining through age, which is what this study shows, but it means we also have this timebomb, which is that the sons we conceive when we are 40 are more likely to (have] Y-chromosome deletions, and infertility problems when they grow up, than those we conceive when we are 20."

Yet, Shaw argues, governments and society demand that men and women put off childrearing until a later stage in our lives and pursue careers. "We berate our teenage pregnancies, but that's what nature used to do when we had communal child-rearing, and that was our natural time to have a baby."

In his view, the really big issue to emerge from the report is that government fails to fund IVF properly when older people eventually want families and seek reproductive medical treatment. "I think that's the really important question arising from all of this."

Of course, for those fathers – and their spouses – who do start families late in life, for career-related or other reasons, the birth is just the beginning. We spoke to two people about the joys and tribulations of late fatherhood.

'You're more mature as a man'

• PAUL JOHNSON is a crime novelist, who has fathered three children since he was 30, the most recent when he was 50. Currently undergoing chemotherapy for cancer, Johnson publishes his tenth novel, The Soul Collector (MIRA Publishers) next month.

I HAD my first child, daughter Silje, now 20, when I was 30; the second, Maggie, now two and a half, when I was 48 and the third, Alex, now six months, when I was 50. So, it was a big gap… not to mention the fact that I'd been told I was infertile after my first cancer in 2003! I married my second wife, Roula, in December 2005 – two weeks before Maggie arrived.

The benefits of late fatherhood are, I guess, that you're more mature as a man. As I'm a self-employed writer, you can whistle for financial stability ... I feel less confident about my grasp of life skills now that I'm older. Having had cancer twice, maybe I'm better at death skills, ha! But I do appreciate being a father more now as a major life-shaping experience. And I have to say that, having had two girls, the arrival of our son has been tremendously uplifting (rugby and rock-music indoctrination has already started).

Another thing I found was that everything I thought I knew about parenting had mysteriously been forgotten, or the fashions had changed. Some kind of weird combination of Darwinism (if you didn't forget, you'd never have any more children) and bourgeois trends (not that I care much about those).

Having less energy is a massive problem, especially post-cancer. As we spend a lot of time in Greece, the Mediterranean family support system is very useful – mothers-in-law, aunties etc. Sleepless nights are part and parcel of being a writer, so there's no major issue there. As I sit at my desk for far too many hours on end, any disruption can only be a good thing. So far as interference with my career is concerned, it certainly hasn't been any more so than cancer.

I'm incredibly lucky to have had the second and third chances of having children with the woman I love. So much for being infertile…

'I wouldn't have had it any other way'

• ALASTAIR DALTON is the transport correspondent of The Scotsman. His son, Jules, was born when he was 40; he is now expecting a second child with his wife, Lindsay.

LIKE many men guilty of a "Peter Pan" attitude to life, I'd always regarded fatherhood – even marriage – as something that could be put off until some vague point in the future. But when I met Lindsay she rightly put me on the spot, not just about getting married, but also in pointing out that if you want to have children, there's no point in hanging about.

We were married in 2003 and Jules was born two years later, when I was 40. It seemed very natural, with many of our friends having children at the same time. Looking back, I wouldn't have had it any other way. One of my younger brothers has three children, the oldest of whom is now 18, and I saw how the needs of a family became his focus at a relatively early age.

Lindsay and I were spending more time at home and in our garden by the time our son was born, so we were ready to make the main sacrifices of time and freedom involved. And even with the great generosity of Jules's relatives, our greater financial stability than earlier in life has also been a key factor – especially in coping with the second-mortgage proportions of nursery costs.

I suppose the pros of later fatherhood are that I feel more ready to be a parent, now that I've shaken off previous fears about "lost youth". Also, I have a home with a garden which is better suited to children than my previous flats. The downside is that, despite my low expectations of spare time, there is indeed very little of it. I'm now also much less able to be flexible at work. because of child-rearing demands.

However, I approached impending fatherhood with a degree of trepidation that life would never be the same again, but I found myself pleasantly surprised. And we've enjoyed the experience so much that we are doing it all again, with number two due in November. Then just watch me eat my words…