* Processes involved in forming reproductive organs can be disrupted in early months of pregnancy
* This also significantly raises men’s risk of illnesses such as cancer in later life
Men trying for fatherhood receive a wealth of lifestyle advice on how best to boost their fertility — wear loose-fitting underpants, avoid hot baths, get a good night’s sleep and steer clear of junk food.
It is advice backed by research — including a study in June, led by Harvard University in the U.S., which found that men (the average age was 19) who ate the most red and processed meat, sugary drinks and starchy carbohydrates had the lowest average sperm counts. On average, these were 25.6 million lower than those who ate the least processed food. (A count of 39 million sperm is normally considered the minimum required to conceive naturally.)
However, scientists are now uncovering a far more worrying truth. It seems that for most men suffering infertility from a low sperm count, the damage was done decades earlier — while they were still in the womb.
Evidence increasingly shows that the delicate processes involved in forming their reproductive organs can be disrupted in the early months of pregnancy, inflicting damage that can harm their chances of fatherhood.
Moreover, new studies suggest that this not only sends their sperm counts plummeting, it also significantly raises men’s risk of serious illnesses such as cardiovascular disease and cancer in later life.
Male fertility is clearly in crisis. A comprehensive review of evidence in 2017, based on 7,500 studies, shows that sperm counts among Western men have more than halved over the past 40 years. The review authors, from the Hebrew University of Jerusalem in the journal Human Reproduction Update, warned that the decline shows ‘no evidence of abating’.
In the UK, around one in ten men of all ages suffers from infertility (defined as unsuccessfully attempting pregnancy for a year or longer), according to research from the London School of Hygiene and Tropical Medicine published in the journal Human Reproduction in 2016.
Other studies indicate that as many as one in five men under 35 has a low sperm count.
British infertility experts are now beginning to explore the root causes of this 21st century plague. Already much of the evidence points to chemical pollutants in the air, water and ground around us as the prime culprit.
There is also evidence that parents’ pre-conception lifestyles may affect their children’s health, and even their fertility, and that the problems may be passed on through the parents’ sperm or eggs by changes in the DNA (known as epigenetic changes).
BORN TO GROW UP INFERTILE?
Today, scientists are starting to discover how the physical damage from these environmental factors or epigenetic changes may begin to develop in the womb.
A leading investigator is Alastair Sutcliffe, professor of general paediatrics at University College London, who is studying data from more then 200,000 men held by the Human Fertilisation and Embryology Authority. He believes that there is a problem of prenatal genetic damage underlying male infertility.
‘Lifestyle is inevitably going to have some impact on your fertility,’ he says. ‘But I think most of the problems with these men probably go back to their days in their mothers’ wombs. For whatever reason, they did not have the right conditions in there.’
This may also have implications for their health.
‘Between 10 and 15 percent of the male genome [the complete set of a man’s DNA] is involved in reproduction,’ says Professor Sutcliffe.
‘If you have a problem with the reproductive side of your genome, then that is probably a window into what’s happening with the whole genome of an individual, so sub-fertile men may have other health issues that are driven by problem genes.’
Indeed, evidence is emerging to link early DNA damage to infertility to men’s subsequent serious illnesses. Last month, for example, a study in the British Medical Journal reported that men with fertility issues face a far higher risk of prostate cancer in later life.
The study of more than 1.2 million men, by researchers from Lund University in Sweden, found that men who became fathers through fertility treatment (IVF or injection of sperm directly into the egg) were far more likely to develop prostate cancer than men whose children were conceived naturally.
INFERTILITY A RED FLAG FOR DISEASE
Professor Sutcliffe believes that risk for diseases such as testicular and prostate cancers may be primed in the womb by the same genetic problems that render men infertile.
He explains: ‘Testicular cancer is an embryonic cancer — which means it is precipitated during development in the womb. But it waits until puberty to begin developing.
‘The risk is written very early in utero. Something similar may be true with prostate cancer.’
As a result, Professor Sutcliffe thinks we may have ‘an obligation’ to screen men for conditions such as prostate cancer in fertility clinics if they are found to have low sperm counts. ‘If their risk of prostate cancer is higher and we can treat their problems before they become serious, we should look for them.’
This finding is only one of a growing number of studies that links low sperm counts in men in their 20s and 30s to serious illness in later life.
In March, researchers at the Johns Hopkins University School of Medicine in Baltimore in the U.S. reported that men who suffer infertility also have a significantly raised risk of non-alcoholic fatty liver disease (NAFLD) — a build-up of fat in the liver which can lead to serious liver damage.
NAFLD is associated with a high risk of other serious conditions such as type 2 diabetes and kidney disease, and is linked to poor diet, lack of exercise and weight gain.
But it may also be that some men are born more susceptible than others. The U.S. researchers suggest that male infertility and NAFLD may be precipitated by the same underlying physiological problems.
Another study last August, of 60,000 infertile men, by British and U.S. scientists, found that those who had undergone vasectomies were at greater risk of high blood pressure and heart disease compared with ones who hadn’t.
This comparison indicates that low or non-existent sperm counts are not themselves the cause of the men’s cardiovascular dangers.
The links between infertility and later ill-health have become compellingly powerful, Christopher Barratt, a fertility researcher and professor of reproductive medicine at Dundee University told Good Health.
‘We have been looking at infertility for a long time, but only recently has attention become more focused on general health,’ he says. ‘The data on this is getting stronger and suggests that if you’ve got sperm problems, you are statistically likely to have more health issues and a greater risk of premature death.’
SO IS PREVIOUS ADVICE WRONG?
What is to become of all the advice for men about protecting their fertility by taking precautions such as wearing loose underpants (to stop overheated testicles killing sperm), cutting out junk food, and so on?
Allan Pacey, professor of andrology at the University of Sheffield, and Britain’s foremost commentator on male fertility, says the advice may still play a crucial role for some men — but we should also face up to the fact that prenatal development now seems to play the major role in determining men’s fertility.
It is known that early pregnancy is a vulnerable period for the healthy development of male reproductive organs. Exposure to plastic is implicated, and mothers’ stress levels have come under the spotlight.
In May, an Australian study of 643 men aged 20 warned in the journal Human Reproduction that men whose mothers were exposed to three or more stressful life events in the first 18 weeks of pregnancy may have an average 38 per cent reduction in the number of sperm as adults.
Professor Pacey told Good Health: ‘I think the single biggest factor is what happens before a man was born — regarding how his testicles were developed. This is determined by how well that first trimester of pregnancy went for him.
‘How that pregnancy expressed itself in a man is determined by the size of his testicles, because that is a result of how they developed in the womb. If you have bigger testicles you produce more sperm — and the more likely they are to produce a baby.
‘If your testicles are small, then that’s likely to be problematic.’
Professor Pacey says that clinics can precisely measure testicle size, but adds: ‘For people at home, the best thing is to measure the testicle inside the scrotum against a lychee. That size is about the minimum volume required for unassisted fertility. Anything smaller may mean problems.’
The significance of this is that, ‘for men who are trying for a family in their late 20s and early 30s, their fertility is already set pretty much completely’, he says.
‘The big issue that doesn’t get publicised is that lifestyle changes have not been proven to make a difference in actually fathering children. If they do make a difference, then it will be comparatively small.’
He explains frankly: ‘All that men can do with lifestyle changes is to protect and promote the testicular function they were born with. It’s about risk reduction.
‘If you have small testicles, your chance of infertility is higher and you have more risk to protect against. A 10 percent reduction of testicular efficiency, for example, is going to have a much greater fertility impact on a man with small testicles than a man with large ones.
‘On the other hand, if men adopt good health habits, then it could help their health in later life.’
So while ‘Look after your swimmers’ may appeal to men’s natural desire to protect their fertility, it may also help keep them healthier in old age. And where’s the harm in that?
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