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Sperm DNA Fragmentation Test: What It Means for Fertility

A sperm DNA fragmentation test (SDF test) looks at the quality of sperm DNA, going deeper than a standard semen analysis. It may highlight issues linked to male infertility, miscarriage, or IVF outcomes — but its role in fertility care is still being researched.

Author

Tassia O’Callaghan

Reviewed by

Kayleigh Hartigan

14 min read

Published 25 October 2025

Spotlight:

  • A DNA fragmentation test looks at sperm DNA quality, not just motility, volume, and morphology.

  • High levels of DNA fragmentation are linked to reduced fertility and higher miscarriage risk.

  • The test is especially useful for couples facing unexplained infertility, repeated IVF failure, or recurrent pregnancy loss.

  • Results can help shape treatment choices, including lifestyle changes, supplements, or advanced IVF techniques.

  • The test isn’t always offered by the NHS, but is widely available at private fertility clinics and specialist andrology centres.

What is a DNA fragmentation test?

A DNA fragmentation test looks at the genetic material inside sperm to check for breaks, or “fragments,” in the DNA strands. Sperm DNA damage can happen during the two months it takes sperm to mature, and higher levels of fragmentation have been linked to problems such as poor embryo development, failed IVF cycles, or miscarriage. [1]

The test itself is simple and non-invasive — it’s done on a semen sample, often alongside other fertility investigations, like a standard male fertility test. Several different methods may be used, and while research suggests a relationship between sperm DNA damage and fertility outcomes, the evidence isn’t always consistent. This means results may guide conversations with your clinic but won’t always change your treatment plan directly.

Why is sperm DNA fragmentation controversial?

Sperm DNA fragmentation (SDF) testing has grown in popularity, but its role in fertility care is still debated. Here’s why:

  • Different guidelines say different things. Some professional bodies, like the European Association of Urology, recommend SDF testing in cases of unexplained infertility or recurrent pregnancy loss. Others, like the American Urological Association, don’t support it as a first-line test. This leaves couples and clinicians with mixed messages. [2,3]

  • No single gold-standard test. Several methods exist (such as TUNEL, Comet, SCSA, and SCD), but they don’t always give the same results, and cut-off values for “normal” vs. “high” vary by lab. That makes it harder to compare studies or standardise care. [4]

  • Conflicting research findings. Some studies link high DNA fragmentation to lower pregnancy rates, poor embryo quality, or higher miscarriage risk. Others show weaker or no associations — especially in ICSI, where the egg may be able to repair DNA damage. [5,6]

  • Practical impact is uncertain. Even if high fragmentation is found, there isn’t always agreement on whether it should change the treatment plan, or which treatment plan is recommended. Some clinics recommend lifestyle changes or antioxidants; others suggest moving directly to ICSI or even testicular sperm retrieval.

Who should do a DNA fragmentation test?

This test may be recommended if:

  • You’ve been trying to conceive for over a year without success — or for six months if the female partner is 35 or older — even when semen analysis or a Fertility MOT has looked “normal.”
  • You’ve experienced repeated miscarriages with no clear explanation. [1]
  • IVF or ICSI cycles haven’t worked, despite good-quality eggs and embryos. [1]
  • The person producing sperm has been exposed to known risk factors like smoking, obesity, varicocele, chronic illness, or exposure to toxins.

How common is DNA fragmentation?

DNA fragmentation in sperm is more common than many people realise. Around 40–50% of men with unexplained (idiopathic) infertility may have high sperm DNA fragmentation (SDF) levels, even when their standard semen analysis looks “normal,” according to recent studies. But it’s worth noting that DNA fragmentation research is still growing, so this figure is an estimate. [7]

In the wider infertility picture, male factors account for about half of all cases of couples struggling to conceive, and elevated DNA fragmentation is now recognised as one of the contributing issues. [8]

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What causes sperm DNA fragmentation?

Sperm DNA fragmentation doesn’t happen for a single reason — it’s usually the result of multiple internal and external stressors combining over time. Below are some of the better-supported contributors, in a tone that speaks to people already navigating fertility challenges:

  • Oxidative stress: An imbalance between damaging free radicals (reactive oxygen species, ROS) and your body’s antioxidant defences is considered a major driver of DNA damage in sperm. [9]

  • Smoking and toxins: Tobacco introduces chemicals and ROS that can break DNA strands; exposure to pesticides, heavy metals, air pollution, and other environmental toxins also correlates with higher fragmentation. [7]

  • Obesity and metabolic changes: Excess weight is linked to higher ROS in semen, hormonal disruption (e.g., increased estrogen conversion), and worsened sperm DNA integrity. [10]

  • Varicocele (enlarged scrotal veins): This condition can raise scrotal temperature, reduce blood flow, cause reflux of toxic metabolites, and impair spermatogenesis — all of which may increase fragmentation. [11,12]

  • Chronic illnesses / systemic stressors: Conditions such as diabetes, hormonal imbalance, infections, or chronic inflammation can elevate oxidative stress and interfere with the maturation of sperm. [7]

  • Viruses and acute illnesses: Viral infections (such as COVID) may temporarily increase oxidative stress or inflammation in the reproductive tract, contributing to DNA damage. (Though direct, high-quality long-term data are limited.) [13]

How is a DNA fragmentation test done?

A DNA fragmentation test is carried out on a semen sample, much like a standard semen analysis — but the laboratory looks deeper at the DNA inside sperm cells. The process is simple and non-invasive:

  • Before the test: You’ll usually be asked to abstain from sex or masturbation for 2–5 days. Longer gaps aren’t recommended, as they can reduce sample quality. It’s also important to let the clinic know about any illnesses or medications, as these may affect results.

  • Producing the sample: A DNA fragmentation test can’t be done at home — the sample needs to be produced on-site at the clinic. You’ll be given a private, discreet room, and masturbation is the only method accepted (lubricants can interfere with results, so they’re not allowed). To avoid contamination, you’ll be asked to wash and dry your hands and genitals beforehand.

  • Collection: The semen is collected into a sterile, pre-labelled container. If any of the sample is missed, especially the first portion (where most sperm are concentrated), the clinic may ask for a repeat.

  • Afterwards: Once the sample is handed over, the laboratory prepares it for analysis using one of several DNA fragmentation testing methods (such as SCSA, TUNEL, Comet, or SCD). Results are usually returned within 1–2 weeks, depending on whether the test is NHS-funded or self-paid.

What is the minimum sperm count for DNA fragmentation test?

Most DNA fragmentation tests need a minimum of around 0.5–1 million sperm per millilitre of semen to run reliably, which would class as a very low sperm count. Some methods, like the Comet or SCSA test, may require slightly more, while others (such as SCD) can work with lower counts or concentrated samples. [3]

If sperm numbers are very low, many clinics can still perform the test by concentrating the sample or, in some cases, using surgically retrieved sperm. So while there is a baseline requirement, having a lower count doesn’t automatically rule out testing — it just means your clinic may adapt the approach.

Can I ask my GP for a DNA fragmentation test?

Yes, you can raise this with your GP — but in the NHS, sperm DNA fragmentation isn’t routinely ordered as a first-line test, so your GP may either request it via your local andrology service or refer you to a fertility clinic that offers it.

If you’re asking your GP, it helps to mention why it’s relevant to you — for example: unexplained infertility, recurrent miscarriage, preparing for IVF, or age over 45 — so they can direct you to the most appropriate pathway.

But if it’s not available locally or waiting times are long, you can self-refer to a private fertility clinic for the same test, at a cost.

Fertility Test: What It Is, What It Costs, and What It Tells You

Whether you’re trying to conceive or simply want to understand more about your reproductive health, a fertility test can help shed light on what’s happening in your body — and what your next steps might be.

Find out more

How much does a DNA fragmentation test cost?

The cost of a DNA fragmentation test in the UK typically ranges between £210 and £499, though prices can vary depending on the clinic, the type of test, and whether it’s part of a broader fertility assessment.

Because clinics structure pricing differently, it’s worth checking what’s included — some bundle semen analysis or consultations within the total, while others list these separately.

  • Test only: Standalone DNA fragmentation tests generally cost £210–£499, depending on the clinic and the laboratory used.

  • Test with package: Many clinics offer combined fertility packages that include a DNA fragmentation test alongside other checks such as sperm count, motility, morphology, and infection screening. These typically start from around £495.

  • Consultation: Understanding what your results mean is an essential part of the process. A follow-up consultation with a specialist may cost an additional £150–£400+, depending on the provider and level of expertise.

  • Lab fees: If you’re using a home collection kit, some clinics may add shipping or handling fees for sample transport and processing.

What do sperm DNA fragmentation results mean?

Your DNA fragmentation test result is usually given as a percentage of sperm with damaged DNA, known as the DNA fragmentation index (DFI). Here’s how most clinics interpret these ranges: [9]

  • Under 15% (normal): Most sperm DNA is intact. Fertility is unlikely to be affected, and treatment outcomes are usually better.

  • 15–30% (moderate): A noticeable proportion of sperm DNA shows damage. This doesn’t rule out pregnancy, but it may reduce success rates and increase miscarriage risk.

  • Over 30% (high): A significant proportion of sperm DNA is fragmented. Research has linked this to poorer embryo development, lower implantation rates, higher miscarriage risk, and even lower average birthweight in babies conceived through IVF or ICSI.

A recent large study of over 6,300 IVF and ICSI patients found that while fertilisation and pregnancy rates weren’t directly affected by higher DFI, miscarriage rates rose as DNA fragmentation increased, and birthweights were lower when DFI was above 15%. This suggests that while sperm DNA fragmentation may not prevent conception, it can influence the health of a pregnancy and, in some cases, outcomes for the baby. [14]

It’s important to remember that results aren’t absolute. Different labs use different cut-offs, and the test is just one piece of your fertility picture. High DNA fragmentation doesn’t mean pregnancy isn’t possible — it highlights where additional support, treatment strategies, or lifestyle changes may be needed.

Next steps after a DNA fragmentation test

Once your DNA fragmentation test is complete, the results will be sent to your referring doctor (or directly to you if you’ve self-funded). What happens next depends on what those results show and your wider fertility history.

If results are reassuring (low fragmentation): Your doctor may continue with your current treatment plan or suggest further investigations to look for other possible causes of difficulty conceiving.

If results show higher fragmentation: This doesn’t mean pregnancy isn’t possible, but it may point to additional support being helpful. Lifestyle changes such as improving diet, reducing smoking or alcohol, and addressing health conditions like obesity or diabetes can make a difference.

For some couples, clinics may recommend advanced treatment options. One example is magnetic activated cell sorting (MACS) combined with ICSI, which helps select the healthiest sperm for fertilisation. Embryos that develop can then be transferred to the womb or frozen for future use. [15]

The most important step after the test is to discuss your results with your doctor or fertility specialist. They can help you understand what your numbers mean in context and guide you towards the next steps that are right for you.

How to fix sperm fragmentation

There’s no one proven treatment that directly “fixes” sperm DNA fragmentation. Most approaches focus on supporting overall sperm health — from lifestyle changes to medical procedures — which may help lower DNA damage depending on the cause. [16,17]

  • Quit smoking, including cigarettes and cannabis

  • Cut back or stop drinking alcohol

  • Maintain a healthy weight

  • Exercise regularly but avoid overheating the testicles

  • Switch to loose-fitting underwear

  • Avoid hot tubs, saunas, or long exposure to heat

  • Improve sleep and lower stress (through relaxation techniques, therapy, or mindfulness)

  • Eat a balanced diet rich in antioxidants

  • Take oral antioxidant supplements, such as vitamin C, vitamin E, selenium, zinc, CoQ10, L-carnitine, or NAC (we don’t recommend starting any supplements without speaking with a medical professional first)

  • Treat underlying infections or inflammation with medication

  • Manage chronic conditions such as diabetes

  • Limit exposure to environmental toxins or pollutants

  • Repair a varicocele surgically, if present

  • Use antioxidant therapy under medical guidance

 

How long does it take for DNA fragmentation to improve?

Sperm take around 2 to 3 months to fully develop, mature, and be released. That means any positive changes you make today — whether it’s lifestyle shifts, supplements, or medical treatment — are most likely to show up in your semen quality after about one full sperm cycle (roughly 5 weeks). [18]

Is the DNA fragmentation test worth it?

Yes, if there are repeated fertility struggles without explanation — it can uncover issues missed by standard semen analysis.

A DNA fragmentation test gives vital insight into sperm quality beyond basic semen analysis. While it’s not always the first test offered, it can make a big difference in understanding fertility challenges, guiding treatment, and improving chances of success. If you’re concerned about sperm quality, miscarriage risk, or repeated IVF failure, this test may provide the clarity you need to move forward with confidence.

Sperm DNA fragmentation FAQs

Can you still get pregnant with DNA fragmentation?

Yes — pregnancy can still happen with sperm DNA fragmentation, but the odds are typically lower and the risks (like poorer embryo development, implantation problems, and a higher chance of miscarriage) are higher as fragmentation rises. [7]

Many couples with sperm DNA fragmentation still conceive naturally and others do well with targeted IVF/ICSI approaches, so if a test shows elevated fragmentation it doesn’t close the door — it just signals that tailored support may help tilt the odds back in your favour.

What is the success rate of IVF with DNA fragmentation?

High sperm DNA fragmentation has been linked to lower IVF success rates, with live births sometimes dropping from around 30% to 15%. With ICSI, the impact is less clear, and using sperm extracted directly from the testicles(which often has less damage) may improve outcomes. [19,20]

What are signs of DNA fragmentation?

There aren’t any obvious physical symptoms of sperm DNA fragmentation — most people only discover it after fertility struggles. Signs can include repeated difficulty conceiving, poor embryo development in the lab, failed implantation, or recurrent miscarriages. Because these issues overlap with many other fertility factors, a DNA fragmentation test is the only way to confirm if damaged sperm DNA is playing a role. [7]

Can stress cause DNA fragmentation?

Yes — stress can contribute to sperm DNA fragmentation. Chronic psychological stress has been linked to higher levels of oxidative stress in the body, which is one of the main drivers of DNA damage in sperm. While stress alone may not cause fragmentation, it can make existing problems worse, especially when combined with other lifestyle or health factors. [7,21]

How does age affect DNA fragmentation?

Sperm DNA fragmentation tends to increase with age. Studies show that men over 40, and especially over 50, are more likely to have higher levels of sperm DNA damage compared to younger men. This is thought to be linked to rising oxidative stress and changes in sperm function over time, which can affect fertility and miscarriage risk. [22,23]

Are most miscarriages caused by DNA fragmentation?

No — most miscarriages are not caused by sperm DNA fragmentation. High DNA fragmentation can raise the risk of miscarriage, especially in cases of recurrent pregnancy loss, but many other factors (such as chromosomal issues, egg quality, or uterine conditions) are more common causes. DNA fragmentation is just one piece of the puzzle. [7,21]

Does high DNA fragmentation cause birth defects?

Right now, there’s no clear evidence that high sperm DNA fragmentation directly causes birth defects. While animal studies suggest possible risks, in humans the egg often has the ability to repair damaged sperm DNA after fertilization. The main concern linked to high DNA fragmentation is reduced fertility or higher miscarriage risk, rather than congenital abnormalities. [7,19,21]

Sources

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