Between all the chemicals found in foods and cleaning products, as well as invasive male contraception techniques, it's surprising to many scientists how males are still fertile after a certain age. However, new research states that there is an age when a man's odds of fathering a child decline rapidly.
After 41 years of age, every year after this becomes a slope downward on the fertility graph, even for health men. And after 45, those who haven't started a family and want one should start doing something about it.
Fertility experts suggest
avoiding chemicals found in many food, cosmetic and cleaning products pose a real threat to male fertility
Professor Richard Sharpe, of the Medical Research Council, warned these hormone-disrupting chemicals are linked to rising rates of testicular cancer and falling sperm counts.
Professor Sharpe said: "Because it is the summation of effect of hormone-disrupting chemicals that is critical, and the number of such chemicals that humans are exposed to is considerable, this provides the strongest possible incentive to minimise human exposure to all relevant hormone disruptors."
Other suggestions include avoiding methods of man-made contraception such as ultrasound blasters and male injections which are adding fuel to this fire further degrading the potential of human fertility.
A new study of IVF patients in which the man's sperm fertilized an egg from a donor has shown interesting results.
In the context of the study, the use of donor eggs allowed the researchers to separate out the effect of the man's age from that of the woman's.
The donor eggs all came from young, healthy women and so any differences in pregnancy rate must be due to the sperm.
And the difference was clear, with fertility declining by up to seven per cent with each extra year on a man's age between 41 and 45. After that, it declined even more rapidly.
The average age of the men whose partners got treatment through IVF was 41.
But the average age of those in which the IVF was unsuccessful was 45, the American Society for Reproductive Medicine's annual conference heard.
The chances of pregnancy fell from 60 per cent at the age of 41 to just 35 per cent for the 45-year-olds.
Researcher Paula Fettback, of the Huntington Medicina Reproductiva clinic in Brazil, said: ‘Age counts, Men have a biological clock too. It is not the same as for women but they can' t wait forever to have children.
‘They have to think about having children, especially after 45.'
A second study presented at the conference backed up the warning.
There, fertility plummeted in male mice from a year old -- equivalent to middle-age in people.
Fewer eggs were fertilised and fewer embryos grew long enough to be used in IVF.
Pregnancies took longer to occur and when they did, the miscarriage rate rocketed from zero using sperm from young animals, to over 60 per cent.
The researchers, from the Colorado Center for Reproductive Medicine, said they believed there would be ‘some parallel' with men.
‘We found an abrupt reproductive deterioration in mid-life, equivalent to humans in their 40s.'
Other studies have found that children of older fathers also run an increased risk of heart defects, autism, schizophrenia and epilepsy, and are almost twice as likely to die before adulthood.
While men constantly make fresh sperm, the ‘machinery' that makes it can slow down and become defective over time. In addition, genetic errors may creep into sperm as men get older.