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The causes and signs of low sperm count

If you’ve been trying for a baby for a while without success or are simply starting to think about your future family, it’s natural to have questions and concerns. For many individuals and couples, male fertility isn’t something that’s discussed openly until it becomes a potential obstacle. Discovering or even suspecting a low sperm count can feel overwhelming, especially when building a family is so important to you.

However, understanding the possible causes and symptoms of low sperm quality is an important step. It can help you make sense of what’s happening, guide you towards the right support, and give you a greater sense of control over your fertility journey. In this article, we’ll explore what low sperm quality means, what might cause it, and how it can affect your chances of conceiving, so you can move forward feeling more informed.

What is sperm count?

Sperm count refers to the number of sperm cells in a sperm sample, and it’s usually measured in millions per millilitre (ml). It’s a key component of overall sperm quality; however, it’s a male fertility myth that it’s the only aspect that influences the chances of conception.

Sperm quality, and therefore, overall fertility, is also determined by:

• Sperm motility: How sperm move
• Sperm morphology: The size, shape and structure of sperm cells
• Sperm vitality: How many sperm are alive in a sample
• pH: The acidity or alkalinity of semen
• Sperm DNA fragmentation: The percentage of sperm with broken or damaged DNA

What is considered a low sperm count?

A normal sperm count is defined by the NHS as more than 16 million sperm more per ml or 39 million sperm per total semen sample. A sperm count below this is considered low and is known as oligospermia. There are different severities of oligospermia:

Mild oligospermia: 10 -15 million sperm per ml

Moderate oligospermia: 5-10 million sperm per ml

Severe oligospermia: 0-5 million sperm per ml

It is thought that around 1 in 3 couples who are having difficulty conceiving will have a diagnosis of oligospermia. If no sperm is detected in the semen at all, this is known as azoospermia.

How to know if you have a low sperm quality

You cannot tell if you have a low sperm count simply by looking at semen by eye. The only way to know if you have a low sperm count is to have a semen analysis test. This involves providing a sample of your sperm that is then lab-tested and examined under a microscope to assess the quality and quantity of the sperm.

Signs and symptoms of low sperm quality

The primary indicator that there may be a low sperm quality is difficulty conceiving, especially if it’s been more than 12 months (although there are other reasons why your partner may not be falling pregnant). You may have no other signs. However, it’s possible to have symptoms of an underlying health condition that is contributing to for instance, a low sperm count. 

Depending on the condition, these symptoms may include:

• Pain, swelling or a lump in the testicles
• Low libido
• Erectile dysfunction
• Decreased facial or body hair
• Causes of low sperm quality

Many different factors can influence your sperm quality. Some of these may be temporary, while others will have a longer-term or permanent impact.

Hormonal imbalance

Specific hormones regulate sperm production, and imbalances in luteinising hormone (LH), or follicle-stimulating hormone (FSH) in particular can disrupt this process. Conditions like hypogonadism or problems with the pituitary or thyroid glands may interfere with hormone levels, leading to reduced sperm production and fertility challenges.

Genetic conditions

Certain inherited conditions can affect sperm production or delivery. For example, Klinefelter syndrome which occurs in men born with an extra X chromosome, can impair testicular function. Other genetic issues, such as Y chromosome microdeletions or cystic fibrosis-related mutations, may also contribute to low or absent sperm counts.

Varicocele

A varicocele is an enlargement of the veins within the scrotum, similar to varicose veins. It can increase the temperature around the testes and affect blood flow, which may reduce sperm production and quality. Varicoceles are a common, treatable cause of male infertility and may not always produce noticeable symptoms.

Infection

Infections in the reproductive tract, such as epididymitis, orchitis, or sexually transmitted infections (STIs), can impair sperm production or block the passage of sperm. Some infections cause inflammation or scarring, potentially leading to long-term fertility issues even after the infection has cleared.

Structural issues

Obstructions or abnormalities in the male reproductive system, such as a blocked vas deferens (the tube that transports mature sperm) or absent seminal vesicles (glands in the male reproductive system), can prevent sperm from being ejaculated. These structural problems may be present from birth or result from surgery, injury, or infection, impacting the sperm count in the semen.

Lifestyle factors

Smoking, excessive alcohol, recreational drugs, and chronic stress can all negatively affect sperm production and quality. Poor sleep and lack of exercise may also play a role. Making positive lifestyle changes can improve sperm health and increase the chances of conception.

Exposure to toxins

Long-term exposure to environmental toxins like pesticides, heavy metals, solvents, or industrial chemicals can reduce sperm count and motility. Men working in certain agricultural, chemical, or manufacturing roles may face increased risk and should consider protective measures to safeguard their reproductive health.

Heat

Sperm production is sensitive to temperature. Regular exposure to high heat, from hot tubs, saunas, tight clothing, or prolonged laptop use on the lap, can impair testicular function. While the effect may be temporary, frequent exposure to heat can reduce sperm count over time.

Medications

Some medications can interfere with sperm production. Anabolic steroids, chemotherapy, testosterone replacement therapy, certain antifungals, and some antibiotics and antidepressants may affect fertility.

Weight

Being overweight or obese can impact fertility by disrupting hormone levels and increasing scrotal temperature. Achieving a healthy weight can improve both general health and reproductive function.

Age

While men remain fertile longer than women, sperm count tends to decrease with age. After age 40, sperm count, motility, and DNA integrity may decline, potentially affecting fertility and increasing the risk of miscarriage or developmental conditions in offspring.

Treatment for low sperm count

In some instances, a low sperm count can be improved. In other circumstances, fertility treatments can be used to overcome the challenges that oligospermia creates when conceiving.

Lifestyle changes

Improving everyday habits can have a significant impact on sperm health. Quitting smoking, reducing alcohol, managing stress, exercising regularly, maintaining a healthy weight and eating a balanced diet may all help boost sperm production and quality. Avoiding heat exposure and environmental toxins can also support fertility.

Surgery

In some cases, surgical intervention may be recommended, particularly for conditions like varicocele or a blocked vas deferens. Corrective surgery may help restore normal sperm flow or improve testicular function. Surgical sperm retrieval may also be used if sperm isn’t present in the ejaculate.

Treatment, medication or supplements

Depending on the underlying cause, hormonal treatments or medications such as gonadotropins or anti-oestrogens may help stimulate sperm production. Antibiotics can treat infections, and certain supplements, like zinc, selenium, or CoQ10, may support sperm health.

Assisted reproductive technology (ART)

If sperm count remains low, techniques such as in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) may be recommended. These treatments allow sperm to be used more effectively, even in very small quantities, and can be successful when natural conception has been challenging.

Donor sperm

When other treatments aren’t successful or suitable, using donor sperm is another option for achieving pregnancy. Donor sperm can be used with IUI or IVF and is often recommended in cases of severely low or absent sperm count. Counselling and support are usually offered as part of this decision-making process.

Understanding the possible causes and treatment options for low sperm count can make the path to parenthood feel less uncertain. Whatever stage you’re at in your fertility journey, know that support and solutions are available. Should treatment with donor sperm be something you are considering, London Sperm Bank is here to help you find a donor.

References

Low sperm count – NHS (January 2024)

NHS 111 Wales – Health A-Z : Low sperm count (oligozoospermia) (October 2023)

Quality statement 4: Semen analysis | Fertility problems (October 2014)

Oligospermia – Jonathan Ramsay – Male Fertility Conditions

Male infertility: Symptoms, causes and treatment | Bupa UK

Sleep and male (In)Fertility: A comprehensive overview – ScienceDirect (June 2025)

Effectiveness of exercise interventions on sperm quality: a systematic review and network meta-analysis – PMC (March 2025)

The association of medications and supplements with human male reproductive health: a systematic review – ScienceDirect (December 2023)

Obesity and male infertility – ScienceDirect (August 2023)