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Condition

Male infertility

Male infertility explained: real causes, how it is diagnosed, and evidence-based treatment options — with sources, not guesswork.

Also known as: male factor infertility, male subfertility

Symptoms5 listed
ICD-10N46.9
Treatable2 options
DE
Medically reviewed by Dr. Elif Yılmaz, MD, FECSM
Last reviewed 22 July 2026
✓ Clinician reviewed
Male infertility✓ Clinician-reviewed information
Key takeaways
  • Infertility is clinically defined as failing to achieve pregnancy after 12 months of regular, unprotected sex — it is about the couple’s outcome, not a single test result on either partner.
  • Male factors are involved in close to half of all infertility cases globally, either alone or alongside a female factor — this is not a rare or marginal contributor.
  • "Male infertility" is not one condition — it is an umbrella term covering hormonal problems, sperm production issues, physical blockages, and a substantial proportion of cases where no clear cause is ever found.
  • Semen analysis is the central diagnostic test, but a single abnormal result is not a diagnosis on its own — sperm parameters vary naturally, and repeat testing is standard practice before drawing conclusions.
  • Many causes of male infertility are identifiable and treatable, and some — including varicocele repair — are among the few genuinely reversible interventions available in reproductive medicine.

Overview

Male infertility means a man’s body is part of why a couple cannot conceive. Doctors call a couple infertile after 12 months of regular sex without a pregnancy. Notice that this is about the couple, not one person. You do not test one partner alone and label them. A man is not simply "fertile" or "infertile" like a yes-or-no blood test. Doctors also split it in two. Primary means no pregnancy has ever happened. Secondary means one has happened before, but not now.

For a long time, people saw infertility as mostly a female issue. The evidence never backed that up. A large WHO study followed more than 8,500 couples across 25 countries. A male factor was involved in nearly half of all cases. It was the only factor in about 19%, and a shared factor in about 26%. So this is common, not rare. Newer data agrees: about one in six people face infertility at some point in life.

"Male infertility" is not one thing. It is a group of causes, sorted by where the problem sits. Some are hormonal. The brain signals that drive sperm-making are off. Some are in the testicles themselves. These include varicocele, genetic causes, or past injury or infection. Some are blockages after the sperm are made. Here the sperm are fine but cannot get out. In many men, all the tests come back and no clear cause is found. Doctors call that idiopathic.

The main test is a semen analysis. It counts the sperm and checks how they move and are shaped. One key point is often missed. A single low result is not a diagnosis by itself. Sperm numbers go up and down over time. A full sperm cycle takes about 72 days. So doctors repeat the test a few weeks later before drawing any firm conclusion.

There is one more reason to take this seriously. Research links male infertility to a slightly higher chance of some heart and metabolic problems later on. So a fertility check can double as a wider health check. This is not meant to scare anyone. Most causes are not linked to serious disease. But a proper check, by someone who knows andrology, is worth more than the fertility answer alone.

A male factor is involved in close to half of all infertility cases — present alone in around 19% of cases and alongside a female factor in a further 26% — which challenges the long-standing but inaccurate assumption that infertility is primarily a women’s health issue.

Types of male infertility

Pre-testicular (hormonal)
Problems with the hormonal signalling from the brain that controls testicular function, including pituitary or hypothalamic disorders, thyroid dysfunction, and hormone suppression from anabolic steroid use.
Testicular
Problems within the testicles themselves, including varicocele, genetic conditions such as Klinefelter syndrome, undescended testicles, injury, prior infection such as mumps orchitis, and damage from cancer treatment.
Post-testicular
Sperm are produced normally but do not reach the ejaculate effectively — including physical blockages, retrograde ejaculation, or ejaculatory dysfunction linked to erectile difficulties.
Idiopathic (unexplained)
No clear cause is identified despite full investigation; this accounts for a meaningful proportion of cases and remains an active area of research.
How common is it?
Roughly one in six people experience infertility at some point in their lifetime, according to WHO’s 2023 global prevalence estimates. Within couples experiencing infertility, a male factor is involved in close to half of all cases — either alone (around 19%) or combined with a female factor (around 26%) — based on a WHO multi-country study of over 8,500 couples across 25 countries.
Source: ncbi.nlm.nih.gov

Symptoms

In most men, no symptoms at all — difficulty conceiving is often the only sign, with semen analysis appearing entirely unremarkable in men without a clear underlying condition
Visible or palpable scrotal changes, such as a varicocele or testicular swelling
Reduced libido, erectile difficulty, or changes in ejaculation, where a hormonal or ejaculatory cause is present
Signs of low testosterone, such as reduced body hair, fatigue, or changes in muscle mass, in some hormonal causes
A history of undescended testicles, testicular injury, mumps as a child, or prior pelvic/prostate surgery — a relevant flag worth mentioning during assessment

Causes

Varicocele — the most common identifiable, surgically correctable cause
Hormonal imbalances, including low testosterone and pituitary or hypothalamic disorders
Genetic conditions affecting sperm production, such as Klinefelter syndrome or Y-chromosome microdeletions
Undescended testicles (cryptorchidism) in childhood, even if surgically corrected
Prior testicular infection, injury, or torsion
Cancer treatment (chemotherapy or radiotherapy) affecting sperm production
Physical blockages in the reproductive tract, including from infection, surgery, or congenital absence of the vas deferens
Retrograde ejaculation or other ejaculatory dysfunction
Erectile dysfunction significantly limiting the ability to have intercourse
Certain medications, including some for prostate and psychiatric conditions, and anabolic steroids
No identifiable cause (idiopathic), in a meaningful proportion of men

Risk factors

Increasing age (a more gradual decline than in female fertility, but a real factor)
Smoking
Heavy alcohol use
Obesity
Anabolic steroid use, current or past
Prolonged heat exposure to the testicles (occupational or lifestyle-related)
Exposure to certain environmental toxins or occupational chemicals
A history of undescended testicles, testicular injury, or mumps orchitis
Prior cancer treatment
Certain chronic health conditions, including diabetes and some autoimmune conditions
Family history of fertility problems or relevant genetic conditions

How it is diagnosed

Assessment typically starts with a detailed history and physical examination. It covers general health, prior surgeries or infections, medication use, lifestyle factors, and family history, alongside an examination that checks testicular size and looks for signs such as varicocele.

Semen analysis is the central diagnostic test, and the WHO’s 2025 guideline recommends it as the first-line triage tool. Using the current WHO 6th edition reference standards, the lower reference limits include a sperm concentration of 16 million per millilitre, total motility of 42%, progressive motility of 30%, and 4% normal forms. These figures are based on the 5th percentile of thousands of fertile men whose partners conceived naturally within a year. Because results vary between samples, a repeat test some weeks later is standard before drawing firm conclusions.

Where semen analysis or history points towards a specific cause, further tests may follow. These include hormonal blood tests (testosterone, and sometimes FSH, LH, and thyroid function), genetic testing in men with very low or absent sperm counts, and scrotal ultrasound to assess for varicocele or other structural findings. This stepwise approach — starting broad, then narrowing based on findings — is the standard recommended in current guidelines, rather than every man automatically receiving every test.

When to see a doctor
  • You and a partner have been trying to conceive for 12 months without success (or 6 months if your partner is over 35)
  • You have a known risk factor, such as a history of undescended testicles, testicular injury, mumps as a child, or prior cancer treatment
  • You notice scrotal swelling, pain, or asymmetry
  • You have symptoms suggesting a hormonal cause, such as reduced libido or signs of low testosterone
  • You have had a vasectomy and are now considering reversal or fertility options
  • You are about to start cancer treatment or another therapy that may affect future fertility

Treatment options

1VaricocelectomyMicrosurgical ligation of dilated scrotal veins to relieve pain and improve semen parameters.2Micro-TESEMicrodissection testicular sperm extraction to retrieve sperm directly from testicular tissue.
Reducing your risk
  • Stopping smoking and moderating alcohol intake are both associated with better semen parameters
  • Managing weight, particularly avoiding obesity, is linked to more favourable hormonal and semen outcomes
  • Avoiding prolonged, repeated exposure of the testicles to heat where practical
  • Discussing anabolic steroid use with a doctor if currently using them, given their well-documented suppressive effect on sperm production
  • Where cancer treatment or other gonadotoxic therapy is planned, discussing sperm banking beforehand is a well-established precaution
  • Prompt treatment of genital infections, since untreated infection can contribute to blockage or inflammation affecting fertility

Common questions

Is infertility really "50/50" between men and women, or is it mostly a female issue?
It is much closer to an even split than public perception often suggests. Large-scale WHO data found a male factor involved in close to half of all infertility cases — either alone or alongside a female factor — which challenges the long-standing but inaccurate assumption that infertility is primarily a women’s health issue.
How long should we try before seeing a doctor?
The standard clinical threshold is 12 months of regular, unprotected intercourse without conception, though this is generally shortened to 6 months if the female partner is over 35. Seeing a doctor sooner is also reasonable if either partner has a known risk factor or specific concern.
Does one abnormal semen analysis mean I am infertile?
No. Semen parameters vary naturally between samples and over time, so a single result below the reference range is not a diagnosis on its own. Current clinical practice, reflected in WHO and other major guidelines, is to repeat testing before drawing conclusions or making treatment decisions.
What is the difference between "infertile" and having a low sperm count?
A low sperm count (oligozoospermia) is one specific finding on a semen analysis and one possible contributor to infertility, but it is not the same thing as infertility itself, and many men with parameters below the reference range still conceive naturally. Infertility is a couple-level clinical outcome; a semen analysis result is one piece of information that feeds into understanding it.
Can male infertility be caused by something that has no symptoms at all?
Yes, and this is actually the most common picture. Most men with male-factor infertility have no symptoms whatsoever and feel entirely well. Difficulty conceiving is often the only sign that prompts investigation, which is part of why semen analysis, not symptoms, is the starting point.
Is male infertility usually treatable?
It depends heavily on the cause. Some causes — including varicocele and certain hormonal imbalances — have well-established, effective treatments. Others, particularly some genetic causes or significant testicular damage, are less directly treatable, though assisted reproductive techniques can often still help couples conceive even when the underlying cause cannot be reversed.
Does age affect male fertility the way it affects female fertility?
Male fertility does decline with age, but more gradually and without as sharp a cut-off as the decline in female fertility. Sperm quality and some semen parameters tend to worsen somewhat with age, and this is increasingly recognised as a genuine, if less dramatic, contributing factor in couples trying to conceive later in life.
Can lifestyle really make a meaningful difference to fertility?
For some men, yes, particularly around smoking, alcohol, weight, and heat exposure, all of which have documented associations with semen quality. That said, lifestyle changes are not a guaranteed fix for every case, and they do not address causes rooted in genetics, structural blockages, or significant hormonal problems.
What is idiopathic male infertility, and how common is it really?
Idiopathic means no clear cause is found even after a full standard investigation — semen analysis is abnormal, but hormones, examination, and other tests do not reveal why. It is a meaningful and commonly cited proportion of cases, and an active area of research, including into tests like sperm DNA fragmentation that are not yet part of routine first-line assessment.
If my semen analysis is abnormal, does that mean surgery is inevitable?
No. Many abnormal findings are managed without surgery — through addressing a reversible cause, lifestyle changes, or moving directly to assisted reproductive techniques such as IUI or IVF/ICSI. Surgery, such as varicocele repair, is one option among several and is only relevant in specific circumstances.
Can a vasectomy be reversed if we change our minds about having children?
Vasectomy reversal is a recognised surgical option and can be successful, though outcomes vary depending on factors including how long ago the vasectomy was performed and individual anatomy. This is a decision worth discussing specifically with a specialist, since success rates and alternatives such as sperm retrieval with IVF both need to be weighed.
Does having had an undescended testicle as a child mean I will definitely have fertility problems?
Not definitely, but it is a recognised risk factor worth mentioning during any fertility assessment, even if it was surgically corrected in childhood. Many men with this history have entirely normal fertility, but it is relevant background for a doctor to have.
Can stress cause male infertility?
Significant, chronic stress has some documented associations with semen quality and hormonal function in research, though it is rarely identified as a sole or primary cause on its own. It is a reasonable factor to mention during assessment, rather than either dismissed entirely or assumed to be the main explanation.
Is it worth getting tested if I already have a biological child?
Yes, if you are now having difficulty conceiving again — this is called secondary infertility, and it has its own distinct causes and investigation pathway. Having previously conceived does not rule out a new or changed fertility issue, including some caused by ageing, new health conditions, or medication changes since the previous pregnancy.
Can certain medications cause infertility, and is this reversible?
Yes — several medication categories, including some for prostate conditions, certain psychiatric medications, and anabolic steroids, are recognised to affect fertility, and effects are often, though not always, reversible after stopping or adjusting the medication. This needs to be discussed with the prescribing doctor alongside whoever is managing the fertility assessment.
Does male infertility mean something is wrong with my overall health?
Not necessarily, but there is a genuine, increasingly recognised association between male infertility and certain other health conditions later in life, which is why some clinicians view a fertility work-up as a useful broader health check. This is not meant to cause alarm — most causes are not linked to serious disease — but it is part of why thorough assessment has value.
Where should I start if I think I might have a fertility problem?
A semen analysis is the standard, low-barrier first step, and can usually be arranged through a GP or directly through a fertility clinic. From there, next steps depend on what the results, history, and examination show — which is exactly why starting with proper assessment, rather than guessing or trying unproven remedies first, tends to be the most efficient path.

Sources

  1. WHO. Guideline for the Prevention, Diagnosis and Treatment of Infertility. Geneva: WHO; 2025. https://www.ncbi.nlm.nih.gov/books/NBK620422/
  2. WHO guideline on infertility: an opportunity to reduce global health inequalities. Lancet Glob Health. 2025. https://www.thelancet.com/journals/langlo/article/PIIS2214-109X(25)00227-X/fulltext
  3. Brannigan RE, et al. Updates to Male Infertility: AUA/ASRM Guideline (2024). J Urol. 2024;212(6):789-799. https://www.auanet.org/guidelines-and-quality/guidelines/male-infertility
  4. WHO Laboratory Manual for the Examination and Processing of Human Semen, 6th Edition. Geneva: WHO; 2021. https://iris.who.int/handle/10665/343208
  5. NHS. Infertility. https://www.nhs.uk/conditions/infertility/