Three things that DO harm male fertility: As phones are linked to lower sperm counts, PROFESSOR ROB GALLOWAY explains why you shouldn’t your mobile just yet

As I write, I have in front of me the printout of a 12-week scan, which reveals the wonderful news that my wife and I are having a baby in May.

As a relatively older dad at 46, I’d been worried about my chances of conceiving. Stories about men (mostly rock stars) old enough to be great-grandads becoming fathers have helped feed the popular belief that age doesn’t affect male fertility.

In fact, that idea was put to bed in 2007 by a study, published in the journal Andrologia, involving more than 6,000 men, which showed that, as you age, sperm count falls; for example, those aged 55 had less than half the number than those aged 30 to 35.

The bad news is that it’s not just about ageing, with data now showing that regardless of age, overall sperm count and the health of those sperm is falling.

A major review published in the journal Human Reproduction Update analysed 223 studies from 1973 to 2018 and found that sperm count had fallen by 68 per cent, and sperm concentration by 51.6 per cent, with the steepest falls occurring after 2000, when there was a drop of 2.6 per cent in sperm concentration every year.

Of course, it’s not just the numbers that matter, it’s also sperm motility (how well they swim) and their morphology (their shape and if they are structurally sound).

But this decline in sperm quantity is a worry; up to one in six couples has difficulty conceiving, with male infertility a factor in half the cases.

What’s going on? Should we blame mobile phones? That was the suggestion of a much-publicised new study in the journal Andrology. The story was covered everywhere, with worrisome headlines. And you know what, the study data really did look pretty scary: a team in Switzerland found that if you used your phone more than 20 times a day, you had a 21 per cent reduction in sperm count compared with those who used it fewer than ten times daily; and for every increase in daily usage (starting from zero), sperm count fell by 1 per cent.

That’s alarming – especially for those of us who always have our phones on daily. But before you ditch your mobile, let me explain what this study didn’t show.

First, even though sperm counts were lower, they were still way above levels that threaten fertility.

Even more significantly, this study looked at semen samples from men aged 18 to 22 at an assessment centre for their physical suitability for army service.

They filled in questionnaires including about their health status, alcohol consumption, weight, smoking and mobile usage and where they usually kept their phone. Surprisingly, where the phone was kept didn’t matter to sperm counts: they dropped regardless of whether men kept their mobile in their trousers or in a bag. But if the phone damaged sperm, surely those who kept their phone in their trousers would be more affected than those who kept the phone in their bags?

That’s one good reason to take this study with a pinch of salt.

The use of mobile phones also had no impact on key aspects of sperm health. In fact, there are hints that it improved it; those who used their phone more than 20 times a day compared with fewer than five times, had better sperm motility and normal morphology. This could be due to chance, but it is still another question mark about the study.

So what did we learn from it? That there is a correlation between higher mobile phone use and lower sperm count. But correlation does not mean it’s a cause.

A great example of this is coffee. For years it had a bad name because studies showed that coffee drinkers were more likely to develop lung cancer. But we now know this was because in the past coffee drinkers were often smokers and it was the smoking causing the cancer, not coffee (which in fact has many health benefits).

The study suggested some other possible causes – the young men who used their mobiles smoked and drank more, and had higher levels of obesity. But then again, even the ‘virtuous’ participants still had lower sperm counts.

I suspect what was really going on was that this study involved young men – 18 to 22-year-olds – and they were probably masturbating more.

Data published in the journal Clinical and Experimental Obstetrics and Gynaecology has shown that the more frequent this behaviour is, the lower volume and concentration of sperm – in other words, it leads to a drop in sperm count (but again, not anywhere near to a level that would affect fertility).

My biggest concern about the new study, and the reason I’m not jumping to get rid of my own mobile phone, is because of the time frame of the research, which ran between 2005 and 2018. During this time, as well as using our phones more, as a population we’ve become unhealthier: we’ve been doing less exercise and eating more processed food (and younger people have been using more illicit drugs such as cannabis, which is known to reduce sperm count).

Maybe these are what caused the declining sperm count, and the fact that the men who used their mobiles more fared worse was just a coincidence.

The bottom line is this new study does not prove that greater mobile phone use has led to dropping sperm counts.

Separately, what we do know is that oxidative stress damages sperm DNA and reduces sperm count, as do lower levels of testosterone. Anything that affects either of these two factors on a population basis would contribute to the falling sperm counts.

Culprits include increasing use of plastics, rising levels of obesity, smoking, alcohol, lack of exercise and poor diet.

So what can you do if you’re worried about your sperm count?

This was something that affected me a couple of years ago: my new partner and I wanted children and the first hurdle we had to overcome was my own self-induced complication, needing to have a vasectomy reversal.

But following the successful operation, we had not conceived after a few months of trying. It was at this point I started to research what could improve our chances.

I identified three factors that weren’t just associated with but were actually proven to help male fertility, with rigorous, randomised controlled trials.

And no, ditching my mobile wasn’t one of them.

The first was losing weight. In a study published in Human Reproduction in 2022, when overweight men – many of them up to 15kg above a healthy BMI – went on an eight-week low-calorie diet (800 calories a day), their sperm count increased by 50 per cent.

These improvements remained for a year in men who maintained the weight loss, but not in men who regained the weight.

Exercise matters, too. When men who went with their partner to a fertility clinic were given an intensive exercise regimen, their sperm count increased by 21 per cent compared with those who didn’t do the exercise, according to a study in 2015 published in the journal Reproduction (the men did a combination of cardiovascular and strength-training exercises). But note, the exercise must not include cycling as the pressure from the saddle on the testicles directly damages sperm.

And finally, diet: this means eating food shown to reduce oxidative stress. In 2018, the American Journal of Clinical Nutrition reported that eating 60g of mixed nuts once a day for 14 weeks increased men’s sperm count and motility and reduced signs of DNA damage.

Other research has shown that taking fish oil could improve sperm motility in infertile men.

I tried all three tactics (at the time I was 10kg too heavy) — and within three months we’d conceived and now have a wonderful son and another baby on the way. (Along with my three pre-vasectomy children!)

The bottom line is that mobile phones may or may not damage sperm. I’ve not stopped using mine, but if you want to protect your fertility, do what we know works: follow the science.

@drrobgalloway