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Condition

Asthenozoospermia (Low Sperm Motility)

Asthenozoospermia is a male fertility condition in which a lower-than-expected proportion of sperm move effectively, reducing their ability to travel through the female reproductive tract and reach an egg. It is identified through semen analysis and may occur alone or together with low sperm count, abnormal sperm morphology, varicocele, infection, genetic disorders, or other causes of male infertility.

Also known as: Low sperm motility, Poor sperm motility, Reduced sperm motility, Weak sperm movement, Slow sperm, Low motile sperm count, Asthenospermia, Asthenozoospermia, Poorly motile sperm, Low progressive motility

Symptoms8 listed
ICD-10N46.9
Treatable1 option
DE
Medically reviewed by Dr. Elif Yılmaz, MD, FECSM
Last reviewed 23 August 2026
✓ Clinician reviewed
Low Sperm Motility✓ Clinician-reviewed information
Key takeaways
  • Asthenozoospermia means sperm motility is reduced, particularly the proportion of sperm moving progressively forward.
  • Diagnosis is made by semen analysis and usually requires confirmation because semen parameters naturally vary between samples.
  • Low sperm motility can occur because of varicocele, infection, oxidative stress, genetic or flagellar abnormalities, lifestyle factors, or other testicular and reproductive conditions.
  • A low motility result does not automatically mean natural conception is impossible.
  • Treatment depends on the underlying cause, while assisted reproductive techniques such as IUI, IVF, or ICSI may be considered when clinically appropriate.

Overview

Asthenozoospermia is reduced sperm motility.

Sperm motility describes how sperm move after ejaculation. For natural fertilization, sperm need sufficient forward movement to travel through the female reproductive tract and reach the egg.

A semen sample contains sperm with different movement patterns.

Laboratories generally assess sperm as:

  • Progressively motile

  • Non-progressively motile

  • Immotile

Progressive motility refers to sperm moving actively forward rather than simply moving in place.

When progressive or overall sperm motility is below the expected reference distribution, the finding may be described as asthenozoospermia.

Why sperm motility matters

Sperm have a long biological journey before fertilization.

After ejaculation, sperm must move through:

  • Cervical mucus

  • Uterus

  • Fallopian tubes

Only a small proportion of sperm ultimately reach the site where fertilization may occur.

Poor motility can reduce the probability that sufficient numbers of sperm successfully complete this journey.

However, fertility cannot be predicted from motility alone.

Sperm concentration, morphology, semen volume, female reproductive factors, timing of intercourse, age, and other variables all influence the probability of conception.

Is low sperm motility the same as male infertility?

No.

Asthenozoospermia is a semen-analysis finding associated with reduced fertility potential, but it does not by itself prove that a man is infertile.

Some men with reduced motility conceive naturally, while others may have difficulty conceiving.

The significance depends on:

  • Degree of motility impairment

  • Total sperm count

  • Total motile sperm count

  • Sperm morphology

  • Presence of additional male-factor abnormalities

  • Female partner factors

  • Duration of infertility

Why one semen test is not always enough

Semen quality naturally varies.

Recent illness, fever, abstinence period, laboratory variation, medications, lifestyle factors, and temporary physiological changes can affect results.

For this reason, an abnormal semen analysis is commonly repeated before concluding that a persistent sperm-motility abnormality is present.

The WHO laboratory manual provides standardized methods for evaluating sperm concentration, motility, morphology, and other semen parameters.

Types of asthenozoospermia (low sperm motility)

Isolated Asthenozoospermia
Sperm motility is reduced while sperm concentration and morphology may otherwise remain within expected ranges. Pure isolated asthenozoospermia is less common than combined semen abnormalities.
Mild Asthenozoospermia
Sperm motility is moderately reduced below the laboratory reference distribution. The clinical significance depends on the total number of progressively motile sperm and other fertility factors.
Severe Asthenozoospermia
Only a very small proportion of sperm demonstrate effective progressive movement. Severe motility impairment may substantially reduce natural conception potential and can prompt investigation for genetic, structural, or functional sperm abnormalities.
Complete Asthenozoospermia
irtually or completely all sperm in the sample appear immotile. This requires careful laboratory evaluation to distinguish immotile but living sperm from sperm that are not viable. Sperm vitality testing becomes particularly important.
Genetic / Flagellar Asthenozoospermia
Poor motility results from abnormalities affecting the sperm flagellum or molecular machinery required for sperm movement. Some severe cases are associated with genetic disorders affecting ciliary and flagellar function.
How common is it?
Asthenozoospermia is one of the most frequently identified semen abnormalities among men undergoing infertility evaluation, but there is no single reliable population prevalence figure because reported rates vary greatly according to the population, laboratory criteria, and whether low motility occurs alone or together with other semen abnormalities.
Source: pubmed.ncbi.nlm.nih.gov

Symptoms

Difficulty conceiving with a partner
Low sperm motility on semen analysis
Reduced progressive sperm motility
Low total motile sperm count
Previous abnormal semen-analysis results
Other semen abnormalities such as low sperm concentration
Varicocele in some men
History suggesting infection, testicular disease, or reproductive dysfunction

Causes

Varicocele
Oxidative stress
Genital tract infection or inflammation
Testicular dysfunction
Genetic abnormalities
Sperm flagellar abnormalities
Primary ciliary dyskinesia
Mitochondrial dysfunction
Exposure to excessive heat
Smoking
Obesity
Certain environmental or occupational toxins
Some medications or medical treatments
Chemotherapy
Testicular injury
Hormonal disorders in selected patients
Prolonged or inappropriate abstinence
Antisperm antibodies in selected cases
Idiopathic causes where no clear explanation is identified

Risk factors

Varicocele
Smoking
Obesity
Metabolic disease
Exposure to excessive testicular heat
Occupational toxin exposure
Previous genital infection
Testicular disease
Previous chemotherapy
Previous testicular injury
Genetic disorders affecting sperm structure
Recent high fever
Increasing age
Poor general reproductive health
Other abnormal semen parameters

How it is diagnosed

Asthenozoospermia is diagnosed primarily through semen analysis.

Semen analysis

A semen sample is examined in an andrology laboratory according to standardized procedures.

Important parameters include:

  • Semen volume

  • Sperm concentration

  • Total sperm number

  • Progressive motility

  • Non-progressive motility

  • Immotile sperm

  • Sperm morphology

  • Vitality when indicated

Motility should be assessed promptly after semen liquefaction because delayed or improper sample handling can affect sperm movement.

WHO semen reference values

The WHO Sixth Edition semen manual provides distributions and lower reference values derived from fertile men.

These values should not be interpreted as a strict boundary between fertile and infertile men.

A result below a reference value indicates that further clinical interpretation may be appropriate, not that natural conception is impossible.

Repeat semen analysis

Because semen parameters fluctuate, an abnormal motility result is generally confirmed with another semen analysis when clinically appropriate.

The clinician considers:

  • Abstinence period

  • Recent fever or illness

  • Sample collection

  • Sample transport

  • Laboratory technique

  • Medications

  • Lifestyle factors

Sperm vitality testing

When a high proportion of sperm are immotile, sperm vitality testing can determine whether they are:

  • Alive but immotile

  • Dead

This distinction is especially important in severe or complete asthenozoospermia.

Medical evaluation

If persistent low motility is confirmed, an andrologist may assess:

  • Fertility history

  • Previous pregnancies

  • Testicular development

  • Varicocele

  • Genital infections

  • Surgery

  • Medications

  • Smoking

  • Heat exposure

  • Occupational exposures

  • Chronic disease

Physical examination may assess:

  • Testicular size

  • Epididymis

  • Vas deferens

  • Varicocele

  • Other genital abnormalities

Hormonal testing

Hormone testing may be appropriate when other findings suggest impaired testicular function.

Potential tests include:

  • FSH

  • LH

  • Total testosterone

  • Prolactin when indicated

Genetic testing

Genetic evaluation may be considered in selected patients with extremely severe motility abnormalities, particularly when a structural sperm-tail disorder or primary ciliary dyskinesia is suspected.

When to see a doctor
  • A semen analysis shows low sperm motility.
  • Repeat semen tests remain abnormal.
  • You and your partner have difficulty conceiving.
  • Almost all sperm are immotile.
  • You have low motility together with very low sperm count.
  • You have a clinically significant varicocele and infertility.
  • You have a history of testicular injury, infection, chemotherapy, or radiation.
  • You have used anabolic steroids or testosterone.
  • You have experienced recurrent respiratory problems together with severe sperm immotility, which can occasionally suggest a ciliary disorder.
  • You want to understand whether natural conception, IUI, IVF, or ICSI is appropriate.

Treatment options

1Varicocele EmbolisationVaricocele embolisation is a non-surgical treatment for varicocele performed through a pinhole in a vein, usually in the groin or the neck. An interventional radiologist threads a fine catheter up into the faulty testicular vein under X-ray guidance and blocks it from the inside using tiny metal coils, a sclerosant liquid, or both, so that blood is rerouted through healthy veins and the pooling around the testicle stops. There is no incision, no stitches, no general anaesthetic and no scrotal wound, and most men are back at a desk within two to five days.
Reducing your risk
  • Stop smoking.
  • Maintain a healthy body weight.
  • Exercise regularly.
  • Avoid anabolic steroid misuse.
  • Avoid unnecessary testosterone therapy when trying to conceive.
  • Limit excessive testicular heat exposure.
  • Use appropriate workplace protection against reproductive toxins.
  • Seek treatment for genital infections.
  • Manage diabetes and metabolic disease.
  • Discuss medications that may affect fertility with a doctor.
  • Avoid excessive alcohol consumption.
  • Maintain balanced nutrition.
  • Seek evaluation for clinically significant varicocele when infertility is present.

Common questions

What is asthenozoospermia?
Asthenozoospermia means sperm motility is reduced. A lower proportion of sperm are able to move effectively forward compared with expected laboratory reference values.
What is low sperm motility?
Low sperm motility means fewer sperm demonstrate effective movement, particularly progressive forward movement.
Can low sperm motility cause infertility?
It can reduce fertility potential because sperm need to move through the female reproductive tract to reach an egg. However, sperm motility is only one component of fertility, and reduced motility does not automatically mean natural pregnancy is impossible.
Can sperm motility improve?
Sometimes. Improvement depends on the cause. Treating a clinically relevant varicocele, addressing infection, stopping reproductive toxins, improving metabolic health, or recovering from temporary illness may improve semen parameters in selected men.
Can varicocele cause low sperm motility?
Yes. Varicocele is associated with impaired semen quality in some men, including reduced sperm motility.
Can smoking reduce sperm motility?
Smoking has been associated with poorer semen quality and increased oxidative stress and may contribute to reduced sperm function.
Does heat affect sperm motility?
Excessive testicular heat exposure can adversely affect sperm production and semen quality. The effect depends on intensity and duration.
Can fever temporarily lower sperm motility?
Yes. Significant fever can temporarily impair sperm production and semen quality. Because sperm development takes weeks, abnormal results may persist for some time after recovery.
What is progressive sperm motility?
Progressive motility describes sperm that move actively forward rather than simply moving in place.
What is total motile sperm count?
Total motile sperm count estimates the overall number of moving sperm in an ejaculate and combines semen volume, sperm concentration, and motility. It can be clinically useful when evaluating fertility and treatment options.
Is zero sperm motility the same as azoospermia?
No. In azoospermia, no sperm are detected in the ejaculate. With complete asthenozoospermia, sperm are present but do not appear to move.
If sperm do not move, are they dead?
Not necessarily. Immotile sperm may still be alive. Sperm vitality testing can distinguish living immotile sperm from non-viable sperm.
Can low sperm motility be treated with supplements?
Some antioxidant and nutritional supplements have been studied, but evidence for improving live-birth outcomes is inconsistent. Supplements should not replace investigation for treatable causes of male infertility.
Can low sperm motility be treated with IUI?
IUI may be considered in selected couples when an adequate number of motile sperm remain after semen preparation. Success depends on the severity of the male factor and female reproductive factors.
Can IVF help with low sperm motility?
Yes. IVF may be considered when fertility is significantly reduced or when other factors are present.
Can ICSI help severe asthenozoospermia?
Yes. ICSI allows an embryologist to inject an individual viable sperm directly into an egg and is commonly used when severe sperm motility problems make conventional fertilization difficult.
Which doctor treats asthenozoospermia?
An andrologist or reproductive urologist specializing in male infertility can investigate persistent low sperm motility and identify potentially treatable causes.

Sources

  1. WHO Laboratory Manual for the Examination and Processing of Human Semen, Sixth Edition https://www.who.int/publications/i/item/9789240030787
  2. EAU Guidelines on Sexual and Reproductive Health — Male Infertility https://uroweb.org/guidelines/sexual-and-reproductive-health/chapter/male-infertility
  3. Asthenozoospermia: Cellular and molecular contributing factors and treatment strategies https://pubmed.ncbi.nlm.nih.gov/31680293/
  4. Human asthenozoospermia: Update on genetic causes, patient management, and clinical strategies https://pubmed.ncbi.nlm.nih.gov/39748639/