What causes fertility problems in men?

Being diagnosed as infertile is often just the start of a long journey in which a couple strives to become parents. As if the diagnosis isn’t devastating enough, often the reasons given for the diagnosis are confusing and peppered with complicated medical terms. This medical jargon can just make the emotional turmoil of infertility even worse, as it feels so alien and detached from what couples are actually feeling and going through.

And that’s if a reason for infertility can be provided at all. Research has shown that up to 30% of cases of infertility are unexplained, whereas 35% of cases can be attributed to the male partner and the remaining 35% to the female partner.

For natural pregnancy to occur, a woman needs to be ovulating (releasing an egg each month), have one or two working fallopian tubes (which carry eggs to the uterus) and she has to have a uterus in which an embryo is able to implant and grow. A man must produce – and deposit in the vagina – a suitable amount of sperm that function reasonably well. These are the basic ingredients for pregnancy, so fertility problems can usually be linked back to a problem in one of these areas.

To try and help lighten the burden of infertility and to knock down some of the barriers that the complicated medical jargon can cause, we have compiled a guide which explains some of the most common causes of infertility, in simple terms.

Male infertility

Scientists have found that in almost half of the men with irregular sperm quality, the root of the problem is unknown. But for those who do get a reason for their diagnosis, the problem often stems from a factor that damages sperm, the cells and systems that produce sperm, or the machinery that helps sperm reach the vagina. According to two well renowned books – one published in 1988 and the other in 2013 – the common causes of male infertility are:


These are swollen veins that can be found in the testes. Varicoceles can lead to a higher than normal temperature which can disrupt sperm production and damage sperm.

Environmental factors

These are any factors that men are exposed to that can damage their sperm or disrupt the production of sperm. Dangerous factors include heat, toxic chemicals and even too much exercise!


This includes prescribed medication – such as steroids and chemotherapy agents – and non-prescribed or recreational drugs and substances such as tobacco, alcohol and marijuana.


Injuries affecting a man’s reproductive system can lead to fertility problems. Testicular torsion is one example and it occurs when a testicle becomes twisted, leading to its blood supply being cut off. The condition can lead to the death of the testicle if it is not treated.

Photo credit: Foter / CC BY-SA

Immunological problems

Although it seems unusual, some men produce antibodies – immune system cells designed to attack foreign cells – which attack and damage their own sperm. This can kill the sperm or affect their ability to function and fertilise eggs.

Genetic factors

Some men are born with genetic problems that can impair their ability to have children. One example is Klinfelter’s syndrome – which is also known as the XXY syndrome, since it leads to men having an extra X chromosome.

Physical abnormalities

Such abnormalities can sometimes lead to infertility. For example, when men have undescended testes, their testes do not hang below the body in the scrotum as they should do. As they stay within the body, the testes are exposed to high temperatures that disrupt sperm production and damage sperm.

Sexual dysfunction

This is often a psychological problem (although sometimes it can be physical) that can act as a barrier to men having sex. Problems include premature ejaculation, failure to ejaculate or problems achieving and maintaining an erection. Ironically, sometimes the stress of trying to conceive can cause these problems.

Endocrine problems

The endocrine system is made up of a collection of glands that coordinate the release of hormones that control metabolism, growth and development, sexual function, sleep and mood (among many other things). The pituitary gland controls the release of hormones affecting sperm production and sexual behaviour. Abnormalities in the pituitary gland (such as those caused by trauma or disease) disrupt hormone release and therefore sperm production.


Blockages in any area of the reproductive system can damage a man’s chance of conceiving. Obstructions may stop a man from getting an erection or could lead to retrograde ejaculation – where a man ejaculates into his bladder.

Infections and disease

There are many infections and diseases can lead to male fertility problems. Of course, sexually transmitted infections (STIs) – especially chlamydia and gonorrhoea – have a big role in causing male infertility if left untreated. STIs are accountable for 20% of male and female infertility cases. However, other diseases and infections including mumps, malaria and testicular cancer can be damaging to male fertility too.

Advanced male age

Although there is a bit of debate around this, scientists are now pretty sure that older men have a slightly lower quality and amount of sperm than younger men. This can sometimes make it difficult for older men to conceive with their partners.


Of course, the good news is that many of the problems mentioned above can be treated. So many men with some of the problems mentioned above still stand a good chance of becoming a father. There are many options out there when it comes to infertility treatments. Depending on the nature of the fertility problem, men could be treated using medication, surgery or therapy. And sometimes a change in lifestyle is all that’s needed to fix a fertility issue.

Unexplained infertility

This is by far the most frustrating diagnosis to receive, since a couple can’t pin the blame for their infertility on a named factor. This can also make treatment more difficult. However, scientists believe it is possible that sometimes this diagnosis is falsely given to couples just because incomplete or poorly carried out investigations have failed to unearth the root of the problem. It’s likely that this diagnosis will be given out less and less in the future as we develop new tests for types of infertility and as we learn more about exactly how the male and female reproductive systems work.

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