The Cougar phenomenon: why older women should choose young lovers

Women in their 40s should look for younger partners to boost their chances of becoming pregnant, new research suggests

Demi Moore has legendary cougar status, as she got permanent paparazzi attention for her relationship with Ashton Kutcher, who is 15 years younger  

Photo: Rex features

Women hoping to become mothers in their 40s should choose young lovers because they will struggle to have children with men of the same age, new research suggests in a finding dubbed ‘the cougar phenomenon.'

Although there is no male menopause, a new study warns that a biological clock is also ticking for men – and it could stop altogether at around 43.

Researchers from McGill University in Canada found that male age was just as important as women’s age in determining whether couples in their 40s were able to have children.

Previously it was thought that men could go on fathering children indefinitely because they continue to produce new sperm, in contrast to women who have the same eggs from birth.
But scientists now believe that mutations can creep in to sperm reproduction over time.
It means that women in their 40s should look for younger partners to boost their chances of becoming pregnant.
Dr Michael Dahan, of McGill University told a fertility conference in Hawaii that the findings were ‘astounding.’
“We think in younger women, the eggs are such that they can fix any defects of the genetic material of the sperm. But once a woman hits 40, that’s no longer true.
“And the funny thing is that it actually gives a biological argument for the cougar phenomenon of an older woman selecting to be with a younger male.
“What we found astounding is that the average age of the men in the group that is not getting pregnant is relatively young. It’s not the ages that we thought.”
It is the first study to look at the impact of male age for older women and could explain why increasing numbers of women, such as director Sam Taylor-Wood, 47, are choosing younger partners. Her actor husband Aaron Johnson is just 24, and they have two children.
The researchers studied women between 40 and 46 who undertook 904 IVF cycles between 2010 and 2012. In couples where the male was 43 and a half or older, no children were born. But older women with younger partners went on to have babies.
Previous studies have shown the children of men over 55 are at greater risk of autism, bipolar disorder, low IQ and schizophrenia and are likely to be less attractive.
But the new research suggests that even in their early forties, men are already beginning to lose their fertility.
“It’s starting to occur at a very young age,” said Dr Dahan.
“If you have a 37 or 36 year old woman, probably the male age is not such a factor. But once you get to 40 and the changes that go along with reproduction in a 40-year-old woman, that’s where the male age became the factor.
“The reality is that most men are probably with women of a similar age, so as the woman is getting older, the male is also getting older.
“It suggests that once the woman is reaching 40 and the man is in his early 40s as well, that the male is having a biological clock that is contributing to their ability to have a live birth. “
Over the past 40 years the average age of childbearing in England has been increasing steadily for both men and women.
According to the Office for National Statistics the average woman gives birth just a week short of her 30th birthday while first-time mothers are also older, at just over 28. The average age of fathers is now 32 years and six months.
Women are born with all their eggs, but male sperm is constantly replicating. Each time sperm replicates there is a chance for a mutation in the DNA to occur. As men age, they are also exposed to numerous environmental toxins which have been shown to cause DNA mutations in sperm.
Molecular genetic studies have shown that the sperm of older men have far more mutations than those of younger men.
Professor Dagan Wells, a leading fertility expert at Oxford University said that older women may find it easier to get pregnant with a younger man.
"We know that the DNA in the sperm of older men suffers a loss of integrity. The DNA should be a nice long uninterrupted molecule but in older men it breaks up into little bits.
"The egg is rich in enzymes which repairs DNA damage but it could be that (as women age) that the egg is getting more challenged. There might be a tipping point."
It means that men who become fathers in their 50s or 60s are not more virile, they are just likely to have a younger partner whose egg has repaired their mutated sperm.
Professor Charles Kingsland, consultant gynecologist at Liverpool Womens NHS Foundation Trust, added: “There are biological reasons why an older woman would benefit from a younger man.
“Not only are male sperm likely to be healthier but woman live a lot longer."
The research was presented at the American Society for Reproductive Medicine annual meeting in Hawaii.