While Mick Jagger and Rupert Murdoch might suggest otherwise, men's reproductive capacity is affected by age.

So some IVF doctors are now suggesting men of a certain age consider freezing their sperm as an insurance policy, just like some women freeze their eggs.

Key points: New study confirms age-related fertility decline in males

New study confirms age-related fertility decline in males Some fertility researchers say men could consider freezing their sperm if they don't have children when they're young

Some fertility researchers say men could consider freezing their sperm if they don't have children when they're young Others in the field say we should focus on how to get both men and women to have children earlier

At the Fertility Society of Australia conference on Monday, researcher Franca Agresta of Melbourne IVF presented new findings that highlight the decline in male fertility with age.

"There is an ageing effect that men should be aware of," she said.

"It's not surprising given most biological processes are impacted by ageing."

The study looked at the success of IVF couples in which men were either under 40 (with an average age of 33) or over 40 (with an average age of 44).

After analysing more than 1,400 single embryo transfer cycles over five years, the researchers found that when men were under 40, their sperm could lead to at least an early pregnancy in 39 per cent of cases.

For men over 40, this figure fell to 26 per cent, according to the study, which also involved the Royal Women's Hospital and the University of Melbourne.

Ms Agresta said the study ruled out other factors that could affect male fertility, such as sperm that was obviously low quality. Also excluded from the study were couples using intracytoplasmic sperm injection, a specialised form of IVF that aims to treat severe cases of male infertility.

Age-related problems with male sperm can be hard to detect. ( Getty: Agence Photographique BSIP )

To control for any female contribution to infertility, the researchers limited the participating couples to those who had done no more than two cycles of IVF, and where the female was under 35.

Ms Agresta said previous studies had tended to be confounded by one or other of these factors.

"We tried to keep the population as clean as possible as much as we could, to only look at the effect of paternal age."

Both men and women need to think about kids early

Ms Agresta said over a third of treatment cycles in Australia and New Zealand were in men over the age of 40.

Sperm in older men could have more DNA damage from environmental factors or epigenetic changes that affected fertility, she added.

She said it was best if people could have children as early as possible.

"There are two parties in conception, and the sperm and the egg both have an impact on the outcomes."

But, she added, since "life circumstances" didn't always allow for that, men could consider elective sperm freezing.

"If you're approaching your 40s and you want to have children and you haven't had that opportunity, then it's definitely an option," Ms Agresta said.

She said it was much easier and cheaper to freeze sperm than eggs.

Men's fertility declines but no 'male menopause'

The findings supported other studies showing the sperm of older men tends to have more DNA damage and their partners have fewer natural pregnancies and more miscarriages, said endocrinologist Robert McLachlan from Healthy Male, which does research and education on male reproductive health.

But, he said, men's age-related decline in fertility was not as absolute as women's. Every woman eventually reaches menopause and are then unable to conceive, but some men can have kids well into their old age.

"I love gender equity but you don't get gender equity with reproductive ageing, as you know — just ask Mick Jagger. Plenty of men have very healthy kids in their 50s and 60s and 70s," said Professor McLachlan, who is also a consultant for Monash IVF.

Mick Jagger's youngest child was born when the rocker was 73 — but the child's mother was 29. ( Getty Images: Maria Moratti )

While both Jagger and Murdoch had children in their 70s, they did so with much younger women, which would have improved their chances of conceiving healthy children.

Professor McLachlan was not a fan of the idea of elective sperm freezing and doubted many men would take it up, partly because if a man did freeze his sperm it would require invasive treatments for the woman.

"That means his dear partner will have to have in vitro insemination in a clinic to use the frozen sperm he stored five years earlier," he said.

"It's not very romantic is it?"

Age-related fertility decline has implications for sperm donation too. ( Getty: Science Photo Library )

Ageing sperm had also been linked to problems like schizophrenia, dwarfism and autism in children born of older fathers, according to Roger Hart, a professor of reproductive medicine at the University of Western Australia.

"A man over 40 has 10 times the mutational load in his sperm, and a man over 70 has 100 times," he said, adding that this age effect was compounding other factors that were already reducing male fertility such as environmental and lifestyle factors.



Professor Hart, who is also medical director at Fertility Specialists of WA, said his fertility unit set an upper limit for the age of men donating sperm of between 35 and 40.

But he also thought it was unlikely men would take up elective sperm freezing.

"Men tend not to take a very responsible approach to reproduction. Women are a lot more pragmatic about these things," he said.

You can freeze it, but will you use it?

There is also the question of whether men would actually use the sperm they froze.

Evidence suggests most women who have frozen their eggs so far don't seem to be using them, because they get pregnant naturally anyway.

Professor Hart said it was often overlooked that when couples delay having a family that the male partner has usually been involved in the decision.

"We tend to focus on the woman, which is not right," he said.

"Women are for ever being told they're delaying child-bearing, but it's men as well.

"So anything that raises the public awareness of the fact that delaying child-bearing is not good, is important."

Professor McLachlan agreed.

"It's better to try and plan to do things naturally — it's much cheaper and much more fun than assisted reproduction using frozen sperm," he said.

"I wish we could find a way in society to bring forward conception to when it's biologically easier and less interventional. It's a bit sad really that we have to come to this."