Everything you need to know about one of the most common causes of male infertility.

It isn’t a term that rolls off the tongue easily. And, for some couples, who dream of starting their own family, it can become a difficult barrier to overcome on their fertility journey. Oligoteratozoospermia, often referred to as OAT, Oligoteratozoospermia or OTA syndrome, is a condition that encompasses a number of varied conditions that impact the health and performance of sperm. These are, oligozoospermia (low sperm count), asthenozoospermia (poor movement of sperm), and teratozoospermia (abnormal sperm shape). All three of these conditions must be present for OAT to be diagnosed. OAT is the single most common cause of male subfertility, meaning, that although it is possible for pregnancy to occur, it is very unlikely.


Low sperm count or oligospermia


What causes Oligoteratozoospermia?

There are a variety of possible causes for OAT. Although for some men, it is difficult to identify a single cause or even pinpoint a cause at all. Causative factors may be genetic, medical, physical or even the result of lifestyle choices. We explore some of the potential causes of Oligoteratozoospermia in more detail, below:


OAT can result from genetics in cases where a man has been born with a genetic disorder or defect that negatively impacts the performance of his sperm. This could be damage within the sperm cell itself, a defect on the Y chromosome or a recognised genetic disorder like Klinefelter Syndrome. It is difficult to directly ‘treat’ genetic factors, but they can often be overcome with other fertility tools like IVF.


Some medicines can cause the sperm dysfunctions seen within OAT. Steroids, some blood pressure medications, treatments for cancer and depression can impact sperm performance. It’s important that men who take regular medication discuss this with both their fertility doctor and their regular medical providers. It’s important not to simply stop taking regular medication without expert advice from a doctor. There may be a different drug or balance of drugs that can be provided which will have a smaller impact on fertility than your current regime.

Current or past infection or illness can also cause deformities in sperm and affect its production and mobility. An initial fertility exam should identify any infections, particularly in the prostate that could be impacting sperm performance.


Physical trauma to the testes, old age, inflammation, and a range of other physical factors can contribute to Oligoteratozoospermia. Enlargement of the varicocele (inflammation of the veins in the scrotum) is another common cause for OAT. Many of the physical causes of OAT can be successfully treated with medication or a small operation.


Smoking is strongly linked to male infertility, as are high levels of alcohol consumption and obesity (meaning a BMI in excess of 30). Other, perhaps less obvious, lifestyle factors include strenuous riding (horse riding or cycling) and overheating of the testes. Overheating can be caused by overly hot showers and baths as well as tight fitting underwear. Changing high-risk lifestyle factors is often one of the first steps in improving male fertility.

How affect fertility?

When sperm moves slowly, is low in number and is of poor quality this dramatically and negatively impacts a couple’s chances of conceiving naturally. It often creates a condition of subfertility, where, although it is possible for a couple to conceive, it is unlikely and may take much longer than it would for other similar couples. Subfertility is diagnosed after a period of time, often a year, where a couple have had regular unprotected sex and struggled to conceive. Treatment for couples with subfertility as oppose to infertility will differ and may be less immediate and aggressive.

Are there any warning signs?

Many men are unaware they are suffering from Oligoteratozoospermia before they begin to try to conceive. The main warning sign is a prolonged period without conception. Some men may experience swelling in the scrotum, which can be a sign of OAT caused by varicocele. Any man with swelling or discomfort in the scrotum should seek immediate medical attention.

How is diagnosed?

A fertility doctor will carefully investigate a number of factors before providing a diagnosis of Oligoteratozoospermia. This process will include a series of questions about lifestyle and any current or prior medical conditions. These initial investigations will be supplemented by a thorough physical exam, blood testing, and (possibly) genetic testing. Semen and sperm analysis and a scrotal ultrasound are also likely to be part of the diagnostic process. Your fertility specialist will consider the results of all these tests very carefully. If they are able to identify oligozoospermia (low sperm count), asthenozoospermia (poor movement of sperm), and teratozoospermia (abnormal sperm shape) they are likely to make a diagnosis of Oligoteratozoospermia or OAT. They will then discuss treatment options and create a treatment plan.

How many men suffer from Oligoteratozoospermia?

Oligoteratozoospermia is a common condition (affecting nearly one in six men) and a leading cause of subfertility and infertility. Low sperm count, quality, and motility is the cause of a staggering 90% of male infertility. It’s important to recognise, though, that many cases of OAT respond well to treatment and many men who suffer from this condition go on to conceive healthy children. For couples facing Oligoteratozoospermia, it’s recommended to seek expert fertility advice.

What treatments are available?

The treatments for Oligoteratozoospermia are, like the cause of OAT, wide-ranging and can differ significantly from person to person. These are some of the most common treatments methods used to tackle Oligoteratozoospermia:


Medicines can be used to treat infection or address hormonal imbalances. In some cases, it may be useful to alter a man’s current drug combination for unrelated issues to mitigate the impact on his fertility. Sometimes, vitamins and antioxidants will be recommended to create an optimal environment for sperm.


Some physical conditions contributing to OAT may be best treated by surgery. For example, to remove an enlarged varicocele that is affecting blood supply to the scrotum. Most surgeries can be done using minimally invasive techniques to quickly tackle and prevent the issues that are causing Oligoteratozoospermia.

Lifestyle Changes

For some men, lifestyle changes can have a tremendous impact on their Oligoteratozoospermia and may be all that is required to increase the chances of natural conception. Stopping smoking, reducing alcohol consumption and maintaining a healthy diet can all contribute to sperm health.

Sperm Extraction

This process allows for sperm to be removed from the epididymis or testicles. This allows doctors to review and select the best samples for fertilisation to increase the chances of conception. This collected sperm may be used as part of the IVF process.

How can I find out more about Oligoteratozoospermia?

If you are struggling to conceive and are worried that you or your partner may be suffering from Oligoteratozoospermia, then your first step should be to speak to your doctor or a local fertility clinic. Each case of Oligoteratozoospermia is different and detailed investigations can help to determine if the condition is impacting your fertility and what the best treatment options are for your specific circumstances. Remember, you are not alone, with thousands of couples facing and overcoming this condition every year. Being armed with expert knowledge and advice is the best way to improve your fertility and take a step closer to achieving the family you are dreaming of.