Can sperm health contribute to recurrent miscarriage?

After a miscarriage, both partners often search for a reason. Because a pregnancy grows from genetic material carried by both the egg and the sperm, it is natural to wonder whether the male partner’s health could have played a part.

In most cases, a miscarriage cannot be traced to one person or one test result. Many early miscarriages happen because the pregnancy has chromosome abnormalities that arise by chance. When losses happen repeatedly, however, it becomes more reasonable to ask whether factors involving either partner might be contributing.

Understanding what sperm health can and cannot tell us helps couples ask the right questions without placing blame or pursuing tests that are unlikely to change their care.

Can a miscarriage be linked to the male partner?

Pregnancy depends on genetic material from both the egg and the sperm, so factors affecting sperm can, in some cases, influence fertilisation or early embryo development.

This does not mean that poor sperm quality causes most miscarriages. A single miscarriage is common and does not usually point to a fertility problem in either partner.

The male contribution becomes more relevant when losses happen repeatedly, particularly if there has also been difficulty conceiving or if a semen analysis is abnormal. However, a conventional sperm count reveals little about sperm quality, whereas sperm DNA fragmentation has been associated with recurrent pregnancy loss.

Even after investigation, there may be no single explanation. Recurrent miscarriage can have several contributing causes, and in some couples no cause is found.

How can sperm affect early embryo development?

A sperm cell carries half of the nuclear genetic material needed to form an embryo.

After fertilisation, the egg and sperm DNA combine and the embryo begins to divide. In the earliest days the embryo runs largely on the egg’s machinery, but the father’s genes are switched on progressively and become increasingly important as development continues. If the genetic material carried by either cell is damaged, this can affect how the embryo develops.

This is why fertilisation is not the end of the sperm’s role. Damaged sperm DNA may still allow conception, yet if the damage is substantial the pregnancy may not continue.

Researchers have explored whether damage within sperm DNA is linked to poorer embryo development and pregnancy loss. The relationship is real but not simple: finding an association does not prove that sperm caused a particular miscarriage. The quality of the egg, the chromosomes within the embryo, the woman’s age and health, and many other biological factors all influence whether a pregnancy continues.

What is sperm DNA fragmentation?

Sperm DNA fragmentation describes breaks or damage within the genetic material carried by sperm.

A standard semen analysis measures how many sperm are present, how well they move and their shape. It does not assess the condition of the DNA packaged inside them, so a man can have an entirely normal semen analysis and still carry a significant level of sperm DNA damage. A specific DNA fragmentation test is needed to measure this.

Studies have consistently found higher levels of sperm DNA fragmentation among men whose partners have experienced recurrent pregnancy loss, and among couples with unexplained infertility or failed IVF. Even so, the test has limits. Men with raised fragmentation can still father healthy children, and miscarriages still happen when results fall within the expected range. Several different laboratory methods exist, and there is no single universally agreed test or threshold.

Should men have sperm DNA fragmentation testing after miscarriage?

This is an area where guidance genuinely differs, and it is worth understanding why.

For couples being assessed for fertility problems more generally, routine UK guidance from NICE does not recommend sperm DNA fragmentation testing. This is because there is not yet strong evidence that the result reliably changes treatment or improves the chance of a successful pregnancy.

The position is different in the specific context of recurrent miscarriage. Several specialist fertility and urology bodies now take a more supportive view. European and North American reproductive medicine and urology guidance increasingly recommends considering DNA fragmentation testing as part of the assessment of the male partner after recurrent pregnancy loss.

This reflects growing evidence linking sperm DNA damage with miscarriage, while recognising that there is still no agreed approach to managing a raised result and that the evidence continues to develop.

Two important caveats remain. A normal result cannot guarantee that another miscarriage will not happen, and a raised result cannot prove that sperm caused a previous loss.

In practice, the test is not routine or essential, but it may be a reasonable and informative part of a specialist assessment after recurrent loss. This may be particularly relevant where the result could prompt further investigation for treatable causes or influence how assisted conception is approached.

Anyone offered the test, especially privately, should feel able to ask how the result would change their care before deciding whether to proceed.

What can affect sperm health?

Sperm production and quality may be influenced by medical conditions, medicines, lifestyle and recent illness. Many of these act through oxidative stress, an imbalance in the body that can damage sperm DNA.

Relevant factors can include:

• Smoking
• Excessive alcohol consumption
• Recreational drugs or anabolic steroids
• Testosterone treatment
• Genital tract infection or abnormal shared microbiome
• Being significantly overweight
• Recent illness with a high temperature
• A varicocele (enlarged veins around a testicle)
• Hormonal conditions
• Previous testicular injury, surgery or undescended testicles
• Certain medicines or previous chemotherapy
• Some environmental or occupational exposures
• Frequent or prolonged exposure of the testicles to excessive heat
• Abstinence or reduced ejaculation frequency

Not every factor on this list causes infertility or miscarriage. A clinician will consider your wider health, semen analysis, DNA fragmentation and medical history with examination before deciding whether anything needs further investigation.

Tell your clinician if you take testosterone or anabolic steroids or other medicines such as finasteride for hair loss. These can suppress the hormones that stimulate sperm production, even when sexual function feels completely normal.

Can improving sperm health reduce the risk of another miscarriage?

Looking after your general health supports sperm production and may improve the chance of conception. It cannot guarantee that another miscarriage will be prevented. However, many of these changes are worthwhile in their own right, and improvements in sperm DNA quality may appear within days or weeks rather than only after several months, depending on the intervention.

Depending on your circumstances, you may be advised to:

• Stop smoking
• Avoid recreational drugs and anabolic steroids
• Limit alcohol
• Work towards a healthy weight
• Eat a balanced diet
• Exercise regularly
• Avoid frequent or prolonged exposure to excessive heat

If a specific male fertility problem is identified, treatment may be recommended to support the chance of conception. This could include treating an infection or hormonal condition, or considering treatment for a clinically significant varicocele in selected men.

It is not yet firmly established whether these treatments alone reduce the risk of recurrent miscarriage. However, they may improve sperm quality and overall fertility, as well as potentially support the long term health of the man, the couple and any future children.

Couples are sometimes advised to take antioxidants or supplements to improve sperm DNA. Current UK guidance does not recommend supplements, antioxidants or medical treatment for this purpose because convincing evidence of benefit is lacking.

No supplement has been proven to prevent miscarriage. High dose vitamins and antioxidants can also cause side effects or interact with medicines, so discuss any supplement with a clinician before taking it. Supplements should not be relied on without considering all other possible contributing factors.

When should the male partner be assessed after pregnancy loss?

After a single miscarriage, additional male fertility tests are not usually needed unless there are other concerns.

Assessment may be more appropriate if:

• The couple has experienced recurrent miscarriages
• There has also been difficulty conceiving
• A semen analysis or sperm DNA fragmentation test is abnormal
• No sperm, or very few sperm, have been found
• There is a history of undescended testicles, testicular surgery or significant injury
• There are difficulties with erections or ejaculation
• There has been chemotherapy or another treatment that may affect fertility
• Testosterone or anabolic steroids are being used
• There is a personal or family history suggesting an inherited condition

The first investigation is often a semen analysis. However, sperm DNA fragmentation may be more closely associated with recurrent pregnancy loss, even when the sperm count is normal.

A male fertility specialist can also look for potentially treatable conditions, such as a hormonal problem, infection or clinically significant varicocele.

Recurrent miscarriage affects both partners, even though only one person experiences the physical loss. Assessment should therefore consider the couple as a whole rather than assuming that either person is responsible.

Sperm health may contribute in some cases, but there is rarely a single test that explains exactly why a miscarriage happened. A thorough specialist assessment can help identify relevant and sometimes treatable fertility problems, avoid unnecessary investigations and guide the next steps for the couple and the health of a future pregnancy.

About the author

Mr Stephen Gordon is an experienced Consultant Urologist specialising in kidney stones, prostate conditions and modern urological diagnostics. He has led one of the UK’s largest kidney stone treatment units and has extensive expertise in laser treatment, shock wave lithotripsy, keyhole surgery and HoLEP for prostate enlargement. He also provides assessment and treatment for urological cancers, urinary symptoms, male fertility concerns and sexual health, with a strong focus on personalised, evidence-based care.