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Causes of male infertility

Fertility problems commonly affect men, but treatments continue to get better. Read advice from our fertility specialists on what causes male infertility, and when it's time for your swimmers to take a sperm test.

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A quick word about gender

We recognise sex and gender are complex. Because we share fertility advice, we use the terms 'man' and 'male' on this page to describe people who make sperm.

What is infertility?

Male infertility is when you’re unable to make a baby with a fertile female partner without medical help.

It’s also defined as when it takes longer than a year for your partner to fall pregnant when having regular unprotected sex together, though this doesn’t always mean you’re infertile.  

Fertility exists on a spectrum:

  • Optimal fertility - there are little to no delays in conceiving

  • Subfertility - it takes longer but is still possible naturally or with fertility treatment

  • Infertility - pregnancy is unlikely without fertility treatment and or donor sperm

Male infertility is more common than you might think

In the UK, around 1 in 14 men are infertile

What percentage of men are infertile?

Among the general public, it’s thought that around 1 in 14 men are infertile, which is 7%.

In couples struggling to get pregnant:

  • 1 in 3 have male infertility

  • 1 in 3 have female infertility

  • And 1 in 3 have both male and female infertility or unknown factors

But infertility doesn't mean it's the end of the road for parenthood.

At TFP Fertility, we offer a number of treatments for male and female infertility.

Common causes of infertility in men

Sperm quality

Sperm is considered low quality when there are:

  • Low numbers or no sperm in the semen (azoospermia or oligospermia)

  • Sperm that struggle to swim, making it hard for them to reach an egg

  • Sperm with an abnormal shape, size or appearance

Problems with testicles

Damage to your testicles can stop you from making healthy sperm.

This can be from:

  • Infections such as STIs

  • Cancer or tumours

  • Congenital conditions (something you were born with)

  • Injuries or scrotal surgery

It’s not always obvious if there’s a problem with your testicles from looking at them.

Blocked tubes

The tubes that sperm travels through can become blocked, stopping it from leaving the testicles.

These tubes can be blocked due to:

  • Infection

  • Surgery of the bladder, urethra or prostate

  • Swelling

  • Problems with the way they’ve developed


Hypogonadism is a hormone condition where you don’t have enough testosterone.

You can be born with it, or it can develop in later life, which some people call the ‘male menopause’.

Symptoms include:

  • Loss of interest in sex

  • Difficulty getting an erection

  • Difficulty orgasming

  • Muscle weakness

  • Feeling tired

  • Breast growth

  • Testicles becoming smaller

If you're born with hypogonadism, it can delay puberty and development.

Medical treatments

Medicines and drugs that can affect male fertility include:

  • Chemotherapy or radiotherapy to treat cancer

  • Anabolic steroids, which are synthetic hormones taken for medical or personal use

  • Some herbal remedies - cottonseed extract (Gossypol) and thunder god vine extract (Tripterygium wilfordii)

  • Sulfasalazine (aka Azulfidine) – an anti-inflammatory medicine that can temporarily reduce sperm

Illegal drugs may also affect fertility.

Unexplained infertility

For 1 in 4 couples, the cause of infertility is unknown.

This can be difficult news, leaving you feeling helpless about what to do next.

It doesn't mean giving up on your fertility journey.

At TFP Fertility, we help many people experiencing infertility to become parents, whether it's an identifiable issue or unexplained.

What else affects male fertility?

Your lifestyle plays an important part in your overall fertility, including:

  • Alcohol - going alcohol-free improves sperm quality quickly

  • Weight ­- being a healthy weight encourages normal testosterone for healthy sperm

  • Smoking - harmful chemicals impact sperm quality

The good news is that, because the testicles make sperm constantly, any positive changes to your lifestyle could potentially boost your sperm production or quality within weeks or months.


Do I need a sperm test?

If becoming a parent is taking longer than you hoped, it might be time to see a specialist.

Most couples conceive within one year of regular sex.

A fertility test helps you understand your reproductive health, so you can work out a baby-making plan that's on track to succeed.


What male fertility tests are there?

A fertility test looks at the quality of your sperm and can include hormone tests and genetic screening, if appropriate.

A sperm test includes:

  • How many sperm cells are in your semen (the concentration or sperm count)

  • Whether they’re fit enough to swim to the egg

  • If their size and shape are normal

A sperm analysis gives a good indication of whether you’re able to conceive naturally.

Getting started contact us

Speak to a fertility specialist

If you’re worried about your fertility or are struggling to get pregnant, a male fertility test and consultation with a specialist can give you the answers you’re looking for.

Our male fertility treatments

Male fertility treatment

If your fertility tests show that something medical is interfering with your plans to become a parent, it doesn't mean giving up.

There are steps you can take to get your fertility journey on the right path, and our fertility experts will be there to support you along the way.

These treatments can be used to help you conceive with your partner, or with a surrogate if you are a same-sex male couple.

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Find out more at our fertility events

When it comes to infertility, tests and treatment, there’s a lot to take in. Talk to our friendly experts face-to-face at one of our in-person or online events, and get your fertility questions answered.


What are the signs of male infertility?

The main sign of infertility is your partner not getting pregnant within a year of having unprotected sex every 2-3 days.

You might not have any other signs any symptoms, as it depends on the cause.

Other signs of male infertility can include:

  • Problems with ejaculation

  • Cloudy urine after sex

Learn about when to see a specialist for fertility concerns.

Can STIs and infections cause male infertility?

Infections known to cause male infertility include:

  • Chlamydia

  • Gonorrhoea

  • HIV

If left untreated, these infections can damage the testicles, affecting sperm production or sperm quality.

STIs don’t always cause symptoms, which is why it’s important to get tested if you’ve had unprotected sex with someone since your last check up, even if the contact happened a long time ago.

You can also pass them on to your partner, which is a risk to their fertility too.

Not all STIs cause infertility. Herpes and HPV are not linked to infertility.

Is male infertility genetic?

As with most health-related concerns, infertility is likely to have a genetic influence.

But for most people, it’s impossible to say for sure whether infertility is caused by their genetics unless they have a specific condition.

Genetic conditions known to cause male infertility include:

  • Cystic fibrosis (rare)

  • Kleinfelter syndrome (rare)

If you’re worried about a genetic condition affecting your fertility, speak to a specialist.

Does vaping affect male fertility?

While smoking is a well-known factor in reduced fertility, there’s less research on vaping.

It’s too soon to say what its long-term effects could be.

So far, it’s not thought to cause infertility.

Vapes are free from tobacco and many other chemicals that are in cigarettes.

But they still contain nicotine, which affects fertility, along with other substances with unknown effects.

So, while vaping may be an alternative to smoking cigarettes, we recommend staying free from all nicotine-based products.

What happens when you have a sperm test?

Having a sperm test might sound intimidating. Luckily, you don't need to study for this kind of test - but you do need to produce a sample.

When visiting a TFP Fertility clinic, you'll be given a private, comfortable and well-equipped room to make your sample, with as much time as you need.

The results of your sperm test gives a good indication of whether you're able to conceive naturally.

You'll have a consultation with a fertility expert to discuss your next steps on the path to becoming a parent.


Ready to start your fertility journey? We're here for you

Schedule an appointment to start your fertility journey with us.