What is sperm morphology?

What is sperm morphology?

You may have seen “sperm morphology” used a lot when trying to learn about your sperm health. But just what is it?

Here’s your handy guide to everything sperm morphology, from what it is, to how it is tested, and how it can impact your fertility.

What is sperm morphology? 

Sperm morphology is the size and appearance of sperm cells, as seen under a microscope. 

We all know the typical sperm appearance: an oval head with a long tail, like a microscopic tadpole. But did you know that not all sperm fit this standard? There’s a large variation in the size and appearance of sperm, and it’s not uncommon for men to have some abnormal cells. These abnormal cells can have enlarged or tiny heads, crooked tails, or even multiple tails! However, some men have sperm which is 100% abnormal, which is called teratospermia. 

What is sperm morphology?

How does sperm morphology impact fertility?

Generally speaking, it’s understood that  sperm with normal morphology is better at travelling and reaching the egg quickly. This is because its body functions like a little jet, propelling it through the cervix and into the womb. But the truth is that most sperm are not perfect in terms of morphology, in fact most sperm cells are misshapen and abnormal.

According to the World Health Organisation, anything above 4% sperm with normal morphology is considered healthy and typical. But it’s also pretty hard to measure morphology accurately. What’s considered “normal” for sperm is subjective, and scores can vary within the same sample and scoring techniques. Basically, two scientists can look at the same sperm sample with the same scoring categories for normal sperm, and still end up with different results.

There is some evidence to show that infertile men are more likely to have a lower sperm morphology than fertile men. One study found that infertile men had 5.7% normal morphology, while fertile men had 9.9%. But these are still normal and healthy morphology levels, not low enough to suggest they are causing infertility. It doesn’t suggest abnormal morphology causes infertility, but shows that morphology is often connected to other fertility factors like motility. 

Morphology varies a lot, and there is still a connection between poor morphology and infertility. It is hard to say whether morphology impacts fertility directly, but it could form part of the issue.

“Sperm morphology is poorly understood, and it can be subjective. In the lab morphology assessment scores can vary on the same semen sample using the same scoring techniques. Most male fertility experts agree that the role of sperm morphology in predicting pregnancy is unclear, and that it’s a poor predictor of infertility”

Dr Fatin Willendrup, Head of Medical Affairs at ExSeed Health

What causes poor sperm morphology? 

While the causes of poor morphology are sometimes unavoidable circumstances like genetic conditions, there are also a few lifestyle risk factors:

  • Tobacco
  • Alcohol
  • Caffeine
  • increased testicular temperatures 
  • having varicoceles

Even though poor morphology alone isn’t necessarily causing infertility  these factors still do a lot of damage to other aspects of your fertility, sperm quality and your wider health. This may be why men with low sperm motility and concentration have lower morphology. 

Abnormal morphology may not jeopardise your fertility, but it could indicate a problem that does. Sometimes this is due to lifestyle, and other times a condition that may have gone undiagnosed. Check out our blog “Varicocele – your go-to guide” to read more about the symptoms, causes and treatments for varicoceles.

Can you improve sperm morphology? 

Since many of the risk factors for poor morphology are related to environmental and lifestyle choices. You can improve your morphology by cutting these out. Avoiding harmful substances like alcohol, tobacco and caffeine alongside keeping physically active can increase your sperm quality, including your sperm morphology. 

Sperm has a regeneration cycle of around 70 days, meaning every three months you produce a new batch of sperm. So by sticking to a healthier lifestyle for a few months you can see big changes in your sperm. 

How do you test sperm morphology?  

A semen analysis will test sperm morphology alongside motility, concentration and other quality factors. You can have these sperm tests often through your GP if you’ve been struggling to conceive for over a year, and through fertility clinics.

Morphology is tested in a laboratory by placing a portion of the sample onto a glass slide, letting it dry, then staining it with special dye. The dye makes each individual sperm darker and easier to see under a microscope. The cells can then be manually examined, or technicians may use a Computer-Assisted sperm Morphology Analysis (CAMA) to analyse the sperm. Most laboratories will examine and evaluate the sperm cells based on the “Kruger” criteria provided by the World Health Organization (WHO). They’ll use this criteria to examine each sperm and fit them into normal and abnormal categories.

Do you need to test morphology?

If you’ve been struggling to conceive, your sperm morphology alone probably isn’t the culprit. Most men have more abnormal sperm cells than normal ones, and even if someone has more abnormal cells than deemed healthy, poor morphology is more common in men with poor sperm motility. 

Since our kits are for at-home testing (and we’re not  providing you a microscope and biology degree), the ExSeed sperm kit does not test sperm morphology. In most cases male fertility issues are down to low sperm concentration and motility, and you don’t need to head to the doctor to test these. 

With an ExSeed kit, you can test your sperm from the comfort of your own home, and receive your results only minutes later on the app. The test will measure your sperm motility and concentration, and give you a detailed breakdown of your results, what they mean, and how they can be improved. It’s important to go through your fertility journey at your own pace, and with ExSeed you’ll have access to professional advice and guidance to help you along the way.

Of course if poor morphology is a big concern, then you can get a full sperm analysis from your doctor or clinic. Poor morphology is unlikely to be the sole cause of infertility. But, getting the full picture of your sperm can be very beneficial and help you make lifestyle changes to boost your sperm quality.

What if you can’t improve morphology?

If you do get your morphology tested and end up with disappointing results, don’t fret! Men with extremely low normal morphology can still conceive naturally. Men with teratospermia can still conceive successfully even without assistive treatment. In one study of men with 0% normal sperm morphology, 29% went on to successfully conceive compared with 55.6% of controls with normal morphology.

If natural conception looks unlikely or impossible, then assisted fertility treatments are always an option. And having a good grasp of the ins and outs of sperm health before going down the assisted fertility route can be a big help. Check out our blog “How Can A Sperm Test Help Your Assisted Fertility Journey?” to find out more about how a sperm test can help you along the way.


All in all, morphology shouldn’t be something that worries you. Everyone’s body functions slightly differently and varied sperm shape is part of that! Poor morphology isn’t a big risk for infertility or difficult pregnancies. And even if you’re someone with 0% normal sperm, you still have a good chance at a successful pregnancy.

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