Infertility is the inability to achieve pregnancy after a defined period of regular, unprotected sex. In most cases, doctors use 12 months as the cutoff for couples when the female partner is under 35, and 6 months when the female partner is 35 or older. Infertility is not only a women’s health issue. It can involve the male partner, the female partner, both, or sometimes no clear cause is found even after testing.
For men’s health, the infertility definition matters because it often connects to sperm count, sperm motility, sperm morphology, hormones, sexual function, genetics, and overall health. Understanding what infertility means is the first step toward getting the right testing, treatment, and next steps.
Table of contents
- Infertility definition at a glance
- What is infertility?
- Primary vs secondary infertility
- What infertility means in men
- Why infertility matters
- Common causes of infertility
- Signs and symptoms
- What’s normal vs what’s not?
- How infertility is diagnosed
- Tests used in infertility evaluation
- Treatment options
- Lifestyle factors and fertility
- Common myths
- Questions to ask your doctor
- Related terms
- FAQs
- References
Infertility definition at a glance
- Infertility means difficulty getting pregnant after a medically defined period of trying.
- It can affect men, women, or both partners. Male factors contribute to a substantial share of infertility cases.
- Male infertility may involve sperm production, sperm delivery, hormones, genetics, testicular function, or sexual dysfunction.
- You can have infertility without obvious symptoms. Many people feel healthy and only discover a problem during fertility testing.
- A semen analysis is usually the first key test in male fertility evaluation.
- Infertility is often treatable with lifestyle changes, medication, surgery, assisted reproductive technology, or a combination.
- Age, time trying, and medical history matter. Earlier evaluation can be especially important when there are known risk factors.
- Infertility can signal broader health issues such as hormone problems, varicocele, genetic conditions, or chronic disease.
What is infertility?
The medical definition of infertility is straightforward: a couple has not conceived despite having regular, unprotected intercourse for a specified amount of time. That timeframe is usually 12 months for most couples and 6 months when age-related fertility decline is more likely to play a role.
Infertility is different from sterility. Sterility generally means pregnancy is not possible without medical intervention, while infertility means pregnancy has not occurred as expected but may still happen naturally or with treatment.
Infertility can be:
- Male factor infertility: a problem related to sperm, semen, hormones, anatomy, ejaculation, erection, or testicular function
- Female factor infertility: issues such as ovulation disorders, blocked fallopian tubes, endometriosis, uterine conditions, or age-related egg decline
- Combined infertility: factors affecting both partners
- Unexplained infertility: standard testing does not identify a clear cause
In real-world use, people often search for “infertility meaning,” “what does infertility mean,” or “definition of infertility.” The practical answer is this: it is a medical term for delayed conception that deserves evaluation, not a personal failure or a judgment about masculinity or health.
Primary vs secondary infertility
Doctors commonly divide infertility into two categories:
| Type | Definition | Example |
|---|---|---|
| Primary infertility | A couple has never achieved pregnancy | They have been trying for 12 months with no prior pregnancies |
| Secondary infertility | A couple has achieved pregnancy before but cannot conceive again | They had a child or prior pregnancy in the past and are now struggling to conceive |
Secondary infertility is often surprising and emotionally difficult because prior pregnancy can create the expectation that conception should be easy the next time. But fertility can change over time due to age, weight changes, hormone shifts, varicocele, medical illness, semen changes, or new reproductive issues in either partner.
What infertility means in men
When people hear the word infertility, they often think first about female reproductive health. But male infertility is common and should be evaluated early. In men, infertility usually means there is a problem with one or more of the following:
- Sperm production: low sperm count or no sperm in the semen
- Sperm movement: poor motility, meaning sperm do not swim well enough to reach the egg
- Sperm shape: abnormal morphology, which can sometimes make fertilization less likely
- Sperm delivery: blockages, ejaculation issues, or structural problems that prevent sperm from entering the semen normally
- Hormonal signaling: low testosterone or problems involving FSH, LH, prolactin, or the pituitary gland
- Testicular function: damage from heat, trauma, infection, undescended testicles, radiation, chemotherapy, or varicocele
- Sexual function: erectile dysfunction, delayed ejaculation, or retrograde ejaculation
- Genetic conditions: chromosome differences or Y chromosome microdeletions that affect sperm production
A man can have infertility even if he has a normal sex drive, normal erections, normal energy, and no symptoms at all. That is one reason semen analysis and fertility workup matter.
Why infertility matters
Infertility matters for more than family planning. It can be a clue to broader health issues. In men, poor fertility may be associated with hormonal disorders, varicocele, genetic conditions, obesity, metabolic disease, prior infections, or environmental exposures. Sometimes infertility is the first reason a man gets a deeper health evaluation.
It also matters emotionally. Difficulty conceiving can cause stress, shame, relationship strain, anxiety, and depression. Men are often less likely to talk openly about fertility concerns, which can delay testing and treatment.
Most importantly, infertility is common enough that it should be treated like a medical issue, not a stigma. A timely evaluation can uncover treatable causes and improve the chances of conception.
Common causes of infertility
Male causes of infertility
Male infertility has many possible causes. Some are reversible, some are manageable, and some require assisted reproduction.
- Varicocele: enlarged veins in the scrotum that may affect testicular temperature and sperm production
- Hormone imbalances: disorders involving testosterone, FSH, LH, thyroid hormone, or prolactin
- Genetic conditions: such as Klinefelter syndrome, Y chromosome microdeletions, or cystic fibrosis-related vas deferens absence
- Obstruction: blockage in the reproductive tract preventing sperm from entering semen
- Testicular damage: due to trauma, infection, undescended testicle, surgery, torsion, radiation, or chemotherapy
- Infections: including some sexually transmitted infections or prior inflammation affecting sperm or reproductive tract function
- Ejaculatory disorders: retrograde ejaculation, anejaculation, or other problems delivering semen
- Sexual dysfunction: erectile dysfunction or inability to have intercourse during the fertile window
- Heat and environmental exposure: repeated high-heat exposure, certain chemicals, solvents, pesticides, or heavy metals
- Medications and substances: anabolic steroids, testosterone therapy, opioids, some antifungals, some chemotherapy agents, excessive alcohol, tobacco, or cannabis
- Lifestyle and health factors: obesity, poor sleep, severe stress, untreated sleep apnea, poorly controlled diabetes, or nutritional deficiencies
Female causes of infertility
Because infertility is a couple-based diagnosis, the female side is also important to evaluate. Common causes include:
- Ovulation disorders such as polycystic ovary syndrome
- Age-related decline in egg quality and egg quantity
- Blocked fallopian tubes
- Endometriosis
- Uterine abnormalities, fibroids, or polyps
- Hormonal conditions such as thyroid disease or elevated prolactin
Unexplained infertility
Sometimes standard testing looks normal, but conception still does not happen. This is called unexplained infertility. It does not mean nothing is wrong. It means current testing has not identified a clear reason.
Signs and symptoms of infertility
The main symptom of infertility is obvious: pregnancy is not happening after the expected period of trying. But some people also have clues that point toward an underlying cause.
Possible signs in men
- Low semen volume
- History of undescended testicle
- Scrotal swelling or heaviness that may suggest varicocele
- Testicular pain or prior injury
- Difficulty with erection or ejaculation
- Low libido
- Reduced facial or body hair, which may suggest hormone problems
- Prior puberty issues or known genetic conditions
Possible signs in women
- Irregular or absent periods
- Very painful periods or known endometriosis
- History of pelvic infection
- Prior tubal surgery or ectopic pregnancy
- Age over 35 with delayed conception
Still, many couples with infertility have no symptoms beyond the inability to conceive. That is why formal evaluation matters.
What’s normal vs what’s not?
There is no single “fertile” number or perfect benchmark that guarantees pregnancy. Fertility is probabilistic, not absolute. Even so, doctors use time-based definitions and semen parameters to guide evaluation.
Trying time: normal delay vs possible infertility
| Situation | Usually considered normal | Usually worth medical evaluation |
|---|---|---|
| Female partner under 35 | Up to 12 months of regular, unprotected intercourse may still be within normal range | No pregnancy after 12 months |
| Female partner 35 or older | A shorter window is used because fertility declines with age | No pregnancy after 6 months |
| Known infertility risk factors | Waiting may not be ideal | Earlier evaluation is often recommended |
Semen analysis: normal vs abnormal
A semen analysis looks at features such as semen volume, sperm concentration, total sperm number, motility, and morphology. A result outside the reference range does not automatically mean pregnancy is impossible. It does mean follow-up may be needed.
| Finding | What it may suggest |
|---|---|
| Low sperm count (oligospermia) | Reduced sperm production or impaired testicular function |
| No sperm in semen (azoospermia) | Blockage or severe sperm production problem |
| Poor motility (asthenozoospermia) | Sperm may struggle to reach and fertilize the egg |
| Abnormal morphology (teratozoospermia) | A higher proportion of sperm have atypical shape |
| Low semen volume | Collection issue, obstruction, hormone issue, or ejaculatory problem |
One semen analysis is not always enough. Sperm parameters can vary over time, and repeat testing is commonly recommended when a result is abnormal.
How infertility is diagnosed
Infertility is diagnosed based on time trying to conceive, plus medical evaluation of both partners when needed. A diagnosis is not made from symptoms alone.
For a man, the workup often starts with:
- Medical history: prior pregnancies, surgeries, infections, medications, testosterone use, anabolic steroids, sexual function, and family history
- Physical exam: testicle size, varicocele, signs of hormone imbalance, and reproductive anatomy
- Semen analysis: usually the first-line laboratory test
- Hormone testing: often including testosterone, FSH, LH, prolactin, and sometimes thyroid studies
- Additional tests when indicated: genetic testing, scrotal ultrasound, post-ejaculate urine, or sperm DNA-related evaluation in select situations
Because infertility is shared across a couple, the female partner should also receive appropriate evaluation. A complete fertility workup is often the fastest route to answers.
Tests used in infertility evaluation
Key male fertility tests
| Test | What it checks | Why it matters |
|---|---|---|
| Semen analysis | Sperm count, concentration, motility, morphology, volume, pH | Often the most important first test in male infertility |
| Total testosterone | Androgen status | Low levels can point to endocrine dysfunction, though testosterone alone does not define fertility |
| FSH and LH | Signals from the brain to the testes | Help distinguish production problems from other causes |
| Prolactin | Pituitary hormone | Abnormal levels may affect sexual and reproductive function |
| Genetic testing | Chromosomal or gene-related causes | Useful in severe sperm abnormalities or azoospermia |
| Scrotal ultrasound | Testicular structure and varicocele | Can reveal anatomic causes |
Related female fertility tests
- Ovulation assessment
- Ovarian reserve testing
- Pelvic ultrasound
- Fallopian tube evaluation
- Uterine cavity assessment
Infertility testing should be individualized. Not every patient needs every test.
Treatment options for infertility
Infertility treatment depends on the cause, age, duration of infertility, semen results, and the goals of the couple. In many cases, treatment focuses on the underlying issue first.
Treatments for male infertility
- Lifestyle changes: weight management, smoking cessation, limiting alcohol, improving sleep, reducing heat exposure, and stopping anabolic steroids or non-prescribed testosterone
- Medication: used selectively for hormone-based problems or some ejaculatory disorders
- Varicocele repair: may improve semen parameters in appropriately selected men
- Treatment of infection or inflammation: when clinically relevant
- Surgical sperm retrieval: used in some men with azoospermia or obstruction
- Assisted reproductive technology: intrauterine insemination (IUI), in vitro fertilization (IVF), or intracytoplasmic sperm injection (ICSI)
Important note about testosterone therapy
Many men are surprised to learn that testosterone replacement therapy can lower sperm production and may worsen fertility. Men trying to conceive should discuss this carefully with a fertility-aware clinician before starting or continuing testosterone.
Treatments involving the female partner
- Ovulation-inducing medication
- Surgery for certain structural issues
- IUI or IVF
- Targeted treatment for endometriosis, tubal disease, or uterine abnormalities
How long does treatment take?
That varies. Since sperm develop over roughly 2 to 3 months, improvements in semen quality may take time to appear after a lifestyle change, medication change, or treatment. Fertility treatment often requires patience and repeated follow-up.
Lifestyle factors that can affect fertility
Lifestyle is not the cause of every infertility case, but it can meaningfully influence reproductive health. Men often ask how to improve fertility naturally. The answer depends on the underlying cause, but these steps are commonly recommended:
- Avoid smoking, including vaping nicotine when possible
- Limit heavy alcohol use
- Avoid anabolic steroids and unprescribed testosterone
- Maintain a healthy weight
- Exercise regularly, but avoid overtraining
- Sleep adequately and address sleep apnea if present
- Manage chronic conditions such as diabetes and thyroid dysfunction
- Reduce excessive heat exposure to the testes when practical
- Review medications with a clinician if fertility is a goal
- Time intercourse around ovulation when appropriate
Supplements are a common search topic, but evidence varies. Some may help in select cases, while others are oversold. It is best to review supplements with a clinician, especially if you are already undergoing fertility testing.
Common myths about infertility
Myth 1: Infertility is mostly a women’s problem
False. Male factors are common and deserve equal attention in evaluation.
Myth 2: If a man can get an erection, he must be fertile
False. Normal erections and normal fertility are not the same thing. A man can have normal sexual performance and still have a sperm problem.
Myth 3: Having one child means future fertility is guaranteed
False. Secondary infertility is real. Fertility can change due to age, health, or new reproductive issues.
Myth 4: A single abnormal semen analysis tells the whole story
False. Semen results can vary, and interpretation should consider repeat testing, medical history, and the partner’s fertility evaluation.
Myth 5: Testosterone boosters always improve fertility
False. Some products marketed for testosterone or muscle gain may harm sperm production, especially anabolic steroids or testosterone therapy.
Questions to ask your doctor about infertility
- Based on our age and history, when should we start fertility evaluation?
- Should I get a semen analysis now?
- Do my medical history, testosterone use, or medications affect fertility?
- What do my semen results actually mean for chances of conception?
- Do I need hormone testing or genetic testing?
- Could I have a varicocele or another treatable cause?
- Would lifestyle changes materially improve my fertility?
- Should we see a reproductive urologist or fertility specialist?
- When is IUI, IVF, or ICSI appropriate?
- How long should we try a treatment before reassessing?
Related tests and terms
- Male infertility: infertility linked to sperm, semen, hormones, or male reproductive anatomy
- Subfertility: reduced fertility; often used less formally to describe delayed conception
- Sterility: complete inability to conceive naturally
- Azoospermia: no sperm seen in the ejaculate
- Oligospermia: low sperm count
- Asthenozoospermia: reduced sperm motility
- Teratozoospermia: increased proportion of abnormally shaped sperm
- Semen analysis: the core lab test for male fertility assessment
- Varicocele: enlarged veins in the scrotum that can affect sperm production
- Unexplained infertility: no clear cause found on standard testing
When to see a doctor
Consider medical evaluation if:
- You have been trying for 12 months without pregnancy and the female partner is under 35
- You have been trying for 6 months and the female partner is 35 or older
- Either partner has known fertility risk factors
- You have a history of undescended testicle, testicular surgery, chemotherapy, pelvic infection, testosterone use, or abnormal puberty
- You have erectile dysfunction, ejaculatory issues, or very low semen volume
- You have had prior abnormal semen analysis results
Earlier evaluation can shorten time to diagnosis and treatment, especially when age or known reproductive issues are involved.
Frequently asked questions
What is the simple definition of infertility?
Infertility is the inability to achieve pregnancy after a medically defined period of regular, unprotected intercourse, usually 12 months or 6 months if the female partner is 35 or older.
What is the difference between infertility and sterility?
Infertility means pregnancy has not happened as expected, but it may still be possible naturally or with treatment. Sterility generally means natural conception is not possible.
Can a man be infertile and still have normal sex drive and erections?
Yes. Fertility and sexual performance are related but not the same. A man can feel completely normal sexually and still have low sperm count, poor sperm motility, or other fertility issues.
Is infertility always caused by low sperm count?
No. Male infertility can also be caused by no sperm in the semen, poor motility, abnormal morphology, blockages, hormone problems, sexual dysfunction, genetic factors, or testicular damage.
How is male infertility diagnosed?
Diagnosis usually starts with a medical history, physical exam, and semen analysis. Depending on the results, a doctor may order hormone testing, imaging, or genetic tests.
Does one abnormal semen analysis mean I am infertile?
Not necessarily. Semen results can vary. A repeat test and full clinical interpretation are often needed before drawing conclusions.
Can infertility be treated?
Often, yes. Treatment may include lifestyle changes, medication, surgery, or assisted reproductive techniques such as IUI, IVF, or ICSI. The right treatment depends on the cause.
Does testosterone therapy help fertility?
Usually not. Testosterone therapy can suppress sperm production and may make fertility worse. Men who want children should discuss alternatives with a knowledgeable clinician.
When should a couple get checked for infertility?
Generally after 12 months of trying if the female partner is under 35, or after 6 months if she is 35 or older. Earlier evaluation may be appropriate when there are known fertility concerns.
Can you have infertility without symptoms?
Yes. Many people with infertility have no obvious symptoms. They only discover a problem after fertility testing.
References
- American Society for Reproductive Medicine (ASRM). Patient education and committee opinions on infertility evaluation and treatment.
- American Urological Association (AUA) and ASRM. Guideline on the diagnosis and treatment of male infertility.
- World Health Organization (WHO). WHO Laboratory Manual for the Examination and Processing of Human Semen.
- National Institute for Health and Care Excellence (NICE). Fertility problems: assessment and treatment.
- Centers for Disease Control and Prevention (CDC). Infertility and reproductive health resources.
- National Institute of Child Health and Human Development (NICHD). Infertility overview and causes.
