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A guide to sperm motility
For fertilisation to occur, individual sperm need to be able to move or ‘swim’ through the vaginal canal, cervix, and uterus to reach an egg as it travels down one of the fallopian tubes. This movement is referred to as sperm motility. It’s an important component of male reproductive health and can impact fertility if it is low.
In this guide, we look at sperm motility in more detail, including what’s considered normal sperm motility, the steps you can take to improve sperm motility and what fertility treatment options you have if your sperm motility is making natural conception challenging.
What is sperm motility?
When we talk about sperm motility, we are talking about how well individual sperm cells move. The sperm must be able to move for it to be able to fertilise an egg inside the female body. This movement is often described as a wriggling or swimming motion where the tail of the sperm moves with a whip-like, side-to-side motion to propel the sperm forward.
There are different types of sperm motility1:
- Rapidly progressive motility: This refers to the percentage of sperm that actively move forward, either in a mostly straight line or in large circles and cover at least half their tail’s length per second.
- Slowly progressive motility: This refers to the percentage of sperm that actively move forward, either in a mostly straight line or in large circles and cover at least one head’s length per second.
- Non-progressive motility: The percentage of sperm that move, but not forward. They may not travel in straight lines or may travel in tight circles.
- Total motility: The total percentage of sperm that moves in any capacity.
- Immotile sperm: This is the amount of sperm that shows no active tail movement at all. Having some non-motile sperm is normal.
How does sperm motility impact fertility?
Reduced sperm motility can reduce the chances of natural conception, as sluggish or non-moving sperm may struggle to travel through the female reproductive system to meet and fertilise an egg. Even if the amount of sperm you have lies within normal parameters, low motility can significantly impact the likelihood of successful fertilisation.
How is sperm motility assessed?
Sperm motility can be determined through a basic semen analysis. Aside from sperm motility, this test examines key aspects of sperm health and semen quality, including:
- Sperm count: how many sperm there are
- Sperm morphology: sperm shape
- Semen volume: how much semen there is
- pH: semen acidity
- Sperm vitality: how many live sperm there are
- Semen viscosity: the thickness and consistency of the semen
- Semen liquefaction: The time it takes for semen to transition from a thick to a watery consistency
For a semen analysis, you’ll need to abstain from ejaculating for 3-5 days and provide a semen sample in a sterile container. This is usually collected in a private room in a hospital or clinic. This will then be examined under a microscope and undergo other assessments.
If your sperm analysis results come back as low, then you’ll typically be asked to repeat the sample three months later to confirm any abnormal results.
Average sperm motility
According to guidelines from the World Health Organization1, a man is considered to have average sperm motility if they have 40% or more total motile sperm or 32% or more progressively motile sperm.
What is considered low sperm motility?
If a man has less than 40% total motile sperm or 32% progressively motile sperm, they are deemed to have asthenozoospermia (reduced sperm motility). This can vary in severity, with complete asthenozoospermia, which is characterised by 100% immotile sperm, occurring in 1 in every 5000 men2.
Does sperm motility decrease with age?
Age can significantly impact overall sperm quality, with studies indicating that men over 50 are more likely to have anomalies in semen volume, and sperm DNA fragmentation, while males over the age of 313 are more likely to have decreased sperm motility. The average sperm count by age also decreases as you get older, making these important considerations in your family planning journey.
What factors affect sperm motility?
Lifestyle and environmental factors contribute significantly to sperm quality and can cause sperm disorders, including low motility. Such factors which can affect sperm motility4 include:
- Environmental toxins
- Smoking
- Radiation
- Heat exposure
- Psychological stress
- Alcohol intake
- High body mass index (BMI)
- Lack of sleep
- Prolonged mobile phone and laptop usage
- Intense physical activity
- Medications
There are also medical conditions and physical health factors that can influence sperm motility, such as:
- Varicoceles
- Infection
- Mitochondrial abnormalities
How to increase sperm motility
Many of the recommended steps to boost sperm motility are the same as those that contribute to good physical health, although there are some lifestyle changes that are particularly beneficial to the testicles, and therefore your sperm.
Advice for how to improve sperm motility5 includes:
- Eat a balanced, nutritious diet rich in leafy greens, fresh fruits, and nuts.
- Quit smoking and steer clear of environments with second-hand smoke.
- Cut back on alcohol, limiting your intake to no more than 5 units a week, ideally spread out across the week. However, avoiding alcohol altogether is best.
- Avoid using recreational drugs.
- Reduce caffeine, which is found in coffee, tea, cola, and energy drinks.
- Choose loose-fitting, boxer-style underwear and avoid overheating your body with hot baths, saunas, or steam rooms. At home, try to go underwear-free if you can.
- Limit long periods of sitting or driving. Aim to take a short break every hour to help regulate scrotal temperature.
- Consider taking supplements such as vitamin C (up to 1000mg daily), along with vitamins A and E, zinc, and selenium within recommended daily limits.
- Minimise exposure to harmful chemicals like solvents and pesticides. Use protective gear such as gloves or masks if needed.
- Manage and reduce stress where possible.
While new sperm are produced every day, it takes 2-3 months for them to reach maturity, meaning that any lifestyle changes you implement can take this long to make a potential difference to your sperm motility and overall quality.
Low sperm motility treatment options
Having low sperm motility doesn’t mean that natural conception is impossible. If the total motility is between 20 and 40%6, you may be able to get your partner pregnant; it might just take a little longer.
However, if your total motility is less than 20%6, conceiving through intercourse is likely to be difficult, and you may want to understand what options you have for fertility treatment.
IVF
In vitro fertilisation (IVF) can help overcome low sperm motility by removing the need for sperm to travel through the female reproductive tract to reach the egg. In IVF, eggs are collected from the ovaries and fertilised with sperm in a lab.
Although IVF typically relies on sperm being able to swim to and penetrate the egg, washed and concentrated sperm samples are used, increasing the chances of successful fertilisation even if the motility of your sperm is lower than average.
ICSI
Intracytoplasmic sperm injection (ICSI) is often recommended when sperm motility is very low. In this procedure, a single healthy-looking sperm is selected and injected directly into an egg, bypassing the need for it to swim or penetrate the egg on its own. This direct method helps maximise the chance of fertilisation when sperm motility issues would otherwise prevent conception, even in IVF.
Donor sperm
When sperm motility is severely impaired, and fertilisation is unlikely with a partner’s sperm, donor sperm may be considered. Donor sperm is carefully screened and typically frozen and stored in one of several donor sperm sample types, such as IUI-ready or IVF-ready samples.
This allows fertility clinics to select the most appropriate sample based on the treatment plan. Sperm donor success rates vary depending on factors like the intended mother’s age and reproductive health, but using donor sperm can offer a reliable path to pregnancy when male factor infertility, including low motility, is a barrier.
London Sperm Bank has helped create over 3,000 babies since 2012, and our success rates exceed HFEA national averages.
If you think fertility treatment with donor sperm is the right path for you, contact us with any questions you may have or learn more about finding a sperm donor.
References:
1 https://iris.who.int/server/api/core/bitstreams/4038e736-37b3-4064-a39a-60475e0ccecc/content
2 https://academic.oup.com/humupd/article-abstract/17/5/684/758230
3 PMC | The effects of aging on semen parameters and sperm DNA fragmentation
5 NHS | Sperm function test results and lifestyle advice for men who ae trying to conceive