MALE FERTILITY • SEMEN ANALYSIS • BRISBANE
Low Sperm Motility: Understanding Asthenozoospermia
Asthenozoospermia means that the proportion of sperm moving normally is below the laboratory reference range. It is often reported as low progressive motility, low total motility, or both.
A low motility result can reduce the number of sperm capable of progressing through the reproductive tract, but it does not by itself diagnose infertility. The significance depends on sperm concentration, total sperm number, morphology, whether sperm are alive, reproductive history and the fertility circumstances of both partners.
Educational information only. A semen-analysis result cannot by itself determine whether a man is fertile or infertile or predict an individual couple's chance of pregnancy.
UNDERSTANDING YOUR REPORT
What does sperm motility measure?
Motility describes how sperm move. Semen laboratories commonly separate motility into sperm that move progressively forward, sperm that move without meaningful forward progression, and sperm that are immotile.
Progressive motility is particularly important because sperm need effective forward movement to travel through the female reproductive tract under natural conditions. Total motility includes both progressive and non-progressive movement.
Asthenozoospermia is generally used when sperm motility falls below the relevant laboratory reference range. It describes the semen finding rather than explaining why it has occurred.
THE REFERENCE VALUES
What is considered low sperm motility?
WHO-derived reference data used in current European guidance list approximately 30% progressive motility and 42% total motility as lower reference limits. These are population reference values, not biological cut-offs that separate fertile from infertile men.
Progressive motility
Approximately 30% progressive motility is the current lower reference limit. A result below this should be interpreted with the rest of the semen analysis.
Total motility
Approximately 42% total motility is the current lower reference limit when progressive and non-progressive sperm are considered together.
What if progressive motility is 20%?
Twenty per cent progressive motility is below the reference range, but its clinical significance depends heavily on sperm concentration, semen volume and the total number of progressively motile sperm available.
What if no sperm are moving?
Complete or near-complete immotility requires careful confirmation. A vitality assessment can help determine whether immotile sperm are alive, and severe persistent cases may justify more specialised investigation.
PUTTING MOTILITY INTO CONTEXT
The percentage is only part of the story
Patients often focus on the motility percentage because it appears to provide a simple measure of how “good” or “bad” sperm movement is. Clinically, the useful question is how motility interacts with the number of sperm present.
A semen sample with a mildly reduced progressive motility but a strong sperm concentration can contain many progressively moving sperm. By contrast, reduced motility combined with a very low sperm concentration can produce a much more significant overall male-factor pattern.
This is why motility should be reviewed together with semen volume, sperm concentration, total sperm number and morphology rather than treated as a standalone result.
POSSIBLE CONTRIBUTORS
Why can sperm motility be low?
Asthenozoospermia is a laboratory description rather than a single diagnosis. There may be one contributor, several contributors, or no clear cause identified.
Normal biological variation
Semen parameters vary between ejaculates. A single mildly abnormal motility result may not represent a persistent problem.
Testicular sperm-production problems
Conditions affecting spermatogenesis may impair several semen parameters at once, including concentration, motility and morphology.
Varicocele in selected men
A clinical varicocele can be associated with abnormal semen parameters. Its significance depends on examination, the complete semen analysis and the couple's fertility circumstances.
Recent illness or heat exposure
Significant febrile illness and marked heat exposure can temporarily affect sperm production and semen quality because sperm development occurs over several weeks.
Reproductive-tract inflammation or infection
In selected clinical settings, inflammation or infection may be relevant. Symptoms, examination and laboratory findings help determine whether further investigation is appropriate.
General health and exposures
Smoking, some occupational or environmental exposures and broader health factors can be associated with poorer semen quality, although an individual result rarely has a single simple explanation.
Structural or functional sperm disorders
Rare men have severe, persistent motility abnormalities related to the sperm tail or its energy-producing structures. These patterns require specialist assessment rather than routine assumptions.
Laboratory and collection factors
Delay in processing, incomplete sample collection and other pre-analytical factors can affect interpretation. The collection history and laboratory report should therefore be reviewed.
No clear cause
Even after appropriate assessment, some men have persistently reduced motility without a single identifiable explanation.
MALE FERTILITY ASSESSMENT
What should be checked after a low motility result?
The appropriate assessment depends on how low the motility is, whether other semen parameters are abnormal and the broader reproductive history.
Review the complete report
Check progressive motility, total motility, concentration, total sperm number, morphology, semen volume and any laboratory comments rather than looking at one percentage alone.
Confirm persistent abnormality when appropriate
If the semen analysis is abnormal, repeat testing can help determine whether reduced motility is persistent rather than the result of normal variation or a temporary factor.
Check collection and laboratory timing
The interval between collection and analysis, whether the complete sample was collected and adherence to laboratory instructions can all influence interpretation.
Review reproductive and medical history
Previous fertility, duration of trying, testicular history, surgery, significant illness, exposures and prior fertility treatment can help identify clinically relevant contributors.
Perform a male reproductive examination
Testicular size and consistency, the epididymis and vas deferens, and the presence of a clinical varicocele or another finding may influence further investigation.
Assess vitality when severe immotility is present
When a large proportion of sperm are immotile, a vitality test can help distinguish living but non-moving sperm from sperm that are not viable.
Select further investigations according to the pattern
Hormonal, genetic or imaging investigations may be appropriate when there are additional clinical indications. Low motility alone does not automatically require every male infertility test.
Consider both partners' fertility circumstances
Female age, ovarian reserve, reproductive history and other fertility factors influence how urgently a male semen abnormality needs to be addressed.
HAVE YOUR SEMEN REPORT?
Interpret motility alongside count and morphology
The Semen Analysis Interpreter helps put progressive motility, concentration, morphology, volume and other semen parameters into context.
FERTILITY IMPLICATIONS
Does low sperm motility mean fertility treatment is required?
Not automatically. The appropriate pathway depends on the severity and persistence of the motility abnormality, how many sperm are present and the couple's complete fertility assessment.
Natural conception may still occur
Reduced motility does not make natural conception impossible. The chance for an individual couple cannot be determined from a motility percentage alone.
Repeat testing may change interpretation
Motility can vary between samples. Confirmation is particularly useful when a result is unexpected or will materially influence fertility planning.
Look for a relevant male factor
Persistent asthenozoospermia may justify male evaluation to determine whether there is an identifiable reproductive or general health issue.
IUI decisions use the processed sperm sample
Whether intrauterine insemination is reasonable depends on the broader semen profile, the number of motile sperm available after laboratory preparation and the couple's circumstances.
IVF or ICSI is not decided by motility alone
Assisted-reproduction strategy is determined with the fertility team using the complete male and female assessment, laboratory findings and any previous fertilisation history.
Severe or complete immotility is different
Near-complete or complete sperm immotility requires more careful assessment of sperm vitality and the underlying pattern than a mildly reduced motility percentage.
WHEN MOTILITY IS VERY LOW
What if motility is close to 0%?
Very low or absent sperm movement is different from a modest reduction in progressive motility. The first step is to confirm the result and determine whether the sperm are alive.
Sperm can occasionally be alive but unable to move normally. Persistent complete or near-complete immotility can also occur in rare structural or functional sperm disorders. In that setting, detailed reproductive assessment may be appropriate.
A single report of severe immotility should not be used in isolation to assume a diagnosis or select fertility treatment.
RELATED MALE FERTILITY INFORMATION
Understand the rest of the semen analysis
MALE REPRODUCTIVE UROLOGY
Individual assessment of abnormal semen results
Dr Jack Crozier is a FRACS-qualified Brisbane urologist with advanced fellowship training in andrology. His practice includes male infertility, abnormal semen analysis, azoospermia, varicocele and microsurgical reproductive urology.
Assessment of asthenozoospermia focuses on confirming whether low motility is persistent, interpreting it alongside sperm number and morphology, and identifying whether there is a clinically relevant male reproductive factor before fertility decisions are made.
FREQUENTLY ASKED QUESTIONS
Low sperm motility and asthenozoospermia FAQs
What is asthenozoospermia?
Asthenozoospermia describes reduced sperm motility on semen analysis. It may involve low progressive motility, low total motility or both. It is a laboratory finding rather than a diagnosis of the underlying cause.
What percentage sperm motility is considered low?
Current WHO-derived reference data use approximately 30% progressive motility and 42% total motility as lower reference limits. These are population reference values, not pass-or-fail fertility thresholds.
Is 20% sperm motility bad?
Twenty per cent progressive motility is below the commonly used lower reference limit, but its significance depends on how many sperm are present, semen volume, other semen parameters and the couple's fertility circumstances.
Can I get my partner pregnant naturally with low sperm motility?
Natural conception can occur despite low motility. A semen motility percentage cannot provide an individual pregnancy probability because sperm number, morphology, reproductive history and female fertility factors also influence conception.
Can sperm motility change between semen analyses?
Yes. Semen parameters naturally vary between ejaculates and can also be affected by recent illness, collection factors and other temporary influences. Repeat testing can be useful when an abnormal result may change clinical decisions.
Does an immotile sperm mean it is dead?
No. Motility and vitality are different. A sperm can be alive but immotile. When motility is very low, laboratory vitality testing can help distinguish living immotile sperm from non-viable sperm.
What does 0% sperm motility mean?
Complete immotility should be confirmed carefully. Laboratory timing and sperm vitality are important, and persistent complete immotility may warrant more specialised investigation.
Can a varicocele cause low sperm motility?
A clinical varicocele can be associated with abnormal semen parameters, including motility, but finding a varicocele does not prove that it is the cause. Its significance depends on examination, semen results and the couple's fertility circumstances.
Can low sperm motility improve?
That depends on the cause and whether the abnormality is persistent. Some temporary influences resolve, while other men have an ongoing sperm-production or sperm-function abnormality. The useful first step is to confirm the result and assess the broader male fertility picture.
Does low motility mean I need IVF or ICSI?
No. Low motility alone does not automatically determine fertility treatment. Decisions about natural conception, IUI, IVF or ICSI depend on the complete semen profile, the fertility assessment of both partners and, where relevant, previous treatment outcomes.
Should I take supplements for low sperm motility?
It is better not to assume that a particular product will correct an abnormal semen result. Evidence and individual circumstances vary, and supplements can have side effects or interact with other treatments. Discuss any products you are taking or considering with your treating clinician.
When should I see a male fertility specialist?
Review is particularly useful when low motility is persistent, substantially reduced, occurs with low sperm concentration or abnormal morphology, follows previous fertility treatment difficulties, or when there are relevant testicular, medical or reproductive-history concerns.
MALE FERTILITY ASSESSMENT
Worried about a low sperm motility result?
A male fertility assessment can review the complete semen analysis, determine whether the finding should be confirmed and assess whether an underlying reproductive issue may be relevant to your fertility plan.