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Eight of the most common causes of male infertility

26 June 2020

No sperm

If you’re not producing any sperm at all in your semen, you’re not going to be able to fertilise your partner’s egg. This condition, known as azoospermia, is the problem for about 15% of men who are infertile, and can be caused by a hormone imbalance or a blockage in the movement of sperm, according to the experts at Stanford Healthcare.


Sperm quantity

If there are fewer than 15million sperm per millilitre of semen that you ejaculate, that’s the clinical definition of a low sperm count. However, that doesn’t mean you’ll be unable to impregnate your partner, but it might just make it harder and less likely.


Sperm quality 

Having said that, even if you’re producing way in excess of 15million sperm per millilitre, you may still have fertility problems due to the quality of the sperm. “If you’ve got a normal, or even high, sperm count it doesn’t guarantee you are fertile and, correspondingly, if you have a very low sperm count, it doesn’t guarantee that you are infertile,” says Richard Sharpe, professor at the University of Edinburgh’s Centre for Reproductive Health.

That’s because other factors can cause fertility problems, such as the mobility, or shape of sperm, both of which could make it far harder for them to reach the egg.



If you’ve never heard of it and would struggle to even say it, then welcome to the leading cause of male infertility, which affects approximately 40% of infertile men (it’s pronounced var-I-co-seal, by the way).
The condition occurs when varicose veins in the testicles become knotted which causes the temperature down there to rise by about four degrees, meaning sperm find it harder to survive.
The good news is that if you have varicocele, you might still be able to help make a baby as it’s estimated that 15% of men who are fertile have the condition.



While it might be counter-intuitive to imagine that ejaculation could be a cause of male infertility, there are some ejaculation disorders which hinder fertility. One of the most common is retrograde ejaculation which is a problem that means semen ends up in the bladder.

According to the Mayo Clinic, it’s possible to treat this condition with medication that helps keep the bladder neck muscle closed during ejaculation, thus ensuring the semen has a better chance of reaching its intended destination.



The older you are, the more likely it is that you may encounter fertility problems. As men age, the quality of sperm is reduced which could make it harder for fertilisation of the egg to occur. Additionally, men also produce fewer sperm as they get older, which also increases the risk of infertility.

Other issues that could impact on fertility which occur as men age include the possibility of erectile dysfunction due to lower testosterone, the reduction of testicle volume, and an enlarged prostate that could affect ejaculation.


Drink and drugs

Excessive alcohol, recreational drugs and steroids can all have a detrimental effect on male fertility, according to research. Additionally, smoking can be damaging. “Male smokers have fewer healthy-shaped sperm than non-smokers,” says Dr Tim Dineen, Head of Laboratory Services at Cork Fertility Centre. “In approximately one-quarter of cases, smoking causes a decrease in sperm quality. Simple lifestyle and diet changes can help to improve the quality of sperm.


Diet and weight

If you’re obese, the chances are you will have lower testosterone and sperm counts, according to many fertility studies. Additionally, a diet without certain vitamins also runs the risk of an increased chance of infertility, with zinc, Omega 3, Vitamins E and B9 (folic acid) all playing important roles in sperm count and quality.

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