trying to conceive

By Lavanya Devakumar

5 Common Causes of Male Infertility & When to Get Tested

 

What are the most common causes of male infertility?

The five most common causes of male infertility are varicocele (enlarged scrotal veins), hormonal imbalances, azoospermia (absent sperm), genetic factors, and lifestyle-related damage from smoking, alcohol, and heat exposure. According to the NIH, male factor infertility contributes to approximately 50% of all cases where a couple cannot conceive. Most causes are diagnosable and many are treatable.

Key Takeaways

  • Male factor infertility is solely responsible in about 20% of infertile couples and a contributing factor in another 30–40%, meaning it plays a role in roughly 50% of all cases

  • Varicocele is the single most common correctable cause of male infertility, found in 40% of men with primary infertility

  • Hormonal imbalances affecting FSH, LH, and testosterone can impair or completely halt sperm production

  • Azoospermia, the complete absence of sperm, affects around 1% of all men and 10–15% of infertile men

  • Lifestyle factors including smoking, alcohol, and heat exposure cause measurable, often reversible damage to sperm quality

  • AUA/ASRM guidelines recommend both partners seek evaluation after 12 months of trying or 6 months if the female partner is 35 or older

  • Both partners matter: a semen analysis is one of the most important and most overlooked steps in fertility evaluation

When you're trying to conceive and it's not happening, the conversation often focuses on the female partner. But the data tells a different story. According to StatPearls/NCBI, male factor infertility is solely responsible in approximately 20% of infertile couples and contributes in another 30–40% of cases. Meaning it plays a role in roughly half of all fertility challenges. Yet male evaluation is still disproportionately delayed or skipped.

Understanding what can go wrong, and what to do about it, is empowering information for any TTC couple. Here are the five most common causes of male infertility, backed by current research.

1. Varicocele: The Most Common Correctable Cause

What is it?

Varicocele is an abnormal enlargement of the veins within the scrotum, essentially varicose veins around the testicles. It is the single most common correctable cause of male infertility, and it's far more prevalent than most people realise.

How common is it?

According to NCBI research, varicocele is found in approximately 40% of men with primary infertility and up to 80% of men with secondary infertility (those who have previously fathered a child but are now struggling to conceive again). It affects around 15% of the general male population.

How does it affect fertility?

Varicocele raises the temperature inside the scrotum. Sperm production requires a temperature slightly below core body temperature, which is why the testicles sit outside the body. Elevated heat from varicocele disrupts sperm development, reducing sperm count, motility (movement), and morphology (shape). It also increases oxidative stress, which damages sperm DNA.

Is it treatable?

Yes. Research published in PubMed shows that varicocele treatment improves pregnancy rates and sperm concentration in infertile men with abnormal semen parameters. Varicocelectomy, surgical repair, improves semen parameters in approximately 65% of treated men. After treatment, semen improvement typically takes 3–6 months.

2. Hormonal Imbalances: When the Body's Signals Break Down

What are they?

Sperm production is regulated by a hormonal chain: the hypothalamus releases GnRH, which signals the pituitary gland to produce FSH (follicle-stimulating hormone) and LH (luteinising hormone), which in turn drive testosterone production and spermatogenesis in the testes. A disruption anywhere along this chain can impair or halt sperm production.

How common are they?

According to NCBI/StatPearls, hormonal evaluation is recommended for all infertile men with low sperm counts, and research published in NIH/PMC indicates that idiopathic male infertility, often rooted in subtle hormonal disruption, accounts for up to 44% of male infertility cases.

What causes hormonal imbalances in men?

  • Hypogonadism (low testosterone), either primary (testicular failure) or secondary (pituitary/hypothalamic dysfunction)

  • Elevated prolactin (hyperprolactinaemia), which suppresses GnRH

  • Thyroid disorders affecting testosterone production

  • Elevated oestrogen, often linked to excess body fat, which suppresses the hormonal axis driving sperm production

  • Anabolic steroid or exogenous testosterone use, which directly suppresses FSH and LH, reducing sperm production significantly

What does testing involve? A standard hormonal panel includes FSH, LH, testosterone, prolactin, and estradiol. Results guide diagnosis: elevated FSH with low testosterone suggests primary testicular failure, while low FSH with low testosterone points to a pituitary or hypothalamic cause, both of which have different treatment pathways.

3. Azoospermia: When No Sperm Are Present

What is it? Azoospermia is the complete absence of sperm in the ejaculate. It is the most severe form of male infertility, but it is not always permanent.

How common is it? NCBI research on azoospermia confirms that azoospermia affects approximately 1% of all men and 10–15% of men with infertility. It is classified into two types:

  • Obstructive azoospermia (OA): Sperm are being produced but cannot reach the ejaculate due to a blockage, caused by prior vasectomy, infection (such as chlamydia or gonorrhoea), congenital absence of the vas deferens (often linked to cystic fibrosis mutations), or previous surgery. OA accounts for approximately 20–40% of azoospermia cases.

  • Non-obstructive azoospermia (NOA): The testes are not producing sufficient sperm. Causes include Klinefelter syndrome (47,XXY), Y-chromosome microdeletions, chemotherapy or radiation damage, and other testicular conditions.

Is there hope? Yes. PMC-published research confirms that with advances in testicular sperm extraction (TESE) and assisted reproductive technology, men with azoospermia, including NOA, are able to biologically father children. Early diagnosis is critical to identifying the right treatment path.

Also read: Sperm Health and Fertility: What Couples Trying to Conceive Should Know?

4. Genetic Factors: When the Cause Is Chromosomal

What are they? Some cases of male infertility have an underlying genetic cause. The most common include:

  • Klinefelter syndrome (47,XXY): The most common chromosomal cause of male infertility, occurring in approximately 1 in 660 men. It typically results in small testes, low testosterone, and azoospermia.

  • Y-chromosome microdeletions: Small deletions in the Y chromosome that affect genes directly involved in sperm production. These are found in approximately 7–10% of men with azoospermia or severe oligospermia (very low sperm count).

  • Klinefelter syndrome and Y-chromosome deletions together account for around 20–25% of all cases of non-obstructive azoospermia, according to research published in NCBI/PMC.

Why does genetic testing matter? Because some genetic conditions can be passed on to offspring. AUA/ASRM guidelines recommend karyotype and Y-chromosome microdeletion analysis for men with azoospermia or severe oligozoospermia, this is not just about diagnosis, but about informed reproductive decision-making.

5. Lifestyle Factors: The Cause Most Within Your Control

What are they? A significant and growing body of research shows that modifiable lifestyle factors directly damage sperm quality, often in ways that are reversible with meaningful changes.

Smoking: NIH-published research confirms that tobacco consumption reduces semen volume and total sperm count, and is associated with increased sperm DNA fragmentation, which can lower fertilisation rates and increase miscarriage risk. The damage is dose-dependent: heavier smokers show worse sperm parameters than light smokers.

Alcohol: Research published in NIH/PMC shows that chronic alcohol use raises sperm DNA fragmentation by a significant magnitude, disrupts the hypothalamic-pituitary-gonadal axis, and can cause testicular atrophy. Heavy drinkers (50–60g/day or more) show consistently reduced semen volume, concentration, motility, and morphology. Even binge drinking episodes can transiently reduce sperm count and motility.

Heat exposure: Prolonged exposure to heat, from hot tubs, saunas, heated car seats, or laptops placed on the lap, raises scrotal temperature and can temporarily impair sperm production. Sperm take approximately 74 days to develop, meaning the effects of heat exposure today may show up in semen analysis results roughly two to three months later.

Other lifestyle factors confirmed by the NIH: According to the NIH's overview of lifestyle influences on male fertility, additional modifiable risk factors include obesity, recreational drug use (particularly anabolic steroids, cannabis, and opioids), psychological stress, exposure to endocrine-disrupting chemicals, and electromagnetic radiation from devices placed close to the body.

The important message: many lifestyle-related sperm quality issues are reversible. Changes made today can reflect in improved semen parameters within three months, the approximate time it takes for a new cycle of sperm to develop.

When Should You Get Tested?

What do AUA/ASRM guidelines recommend?

According to the AUA/ASRM Male Infertility Guideline (2020):

  • Seek evaluation after 12 months of regular, unprotected intercourse without conception (female partner under 35)

  • Seek evaluation after 6 months if the female partner is 35 or older

  • Seek evaluation sooner if the male partner has known risk factors: previous scrotal surgery, chemotherapy or radiation history, history of STIs, undescended testicles, or a family history of genetic conditions affecting fertility

What does male fertility testing involve? 

The first step is a semen analysis, a non-invasive test that evaluates sperm count, concentration, motility, morphology, and semen volume. MedlinePlus/NIH recommends at least two separate semen analyses to account for natural variation (sperm parameters fluctuate with illness, stress, and recent heat exposure). These should be performed at least one month apart.

If semen analysis shows abnormalities, follow-up testing typically includes hormonal evaluation (FSH, LH, testosterone, prolactin), scrotal ultrasound, and where indicated genetic testing.

Don't wait for the female partner's evaluation to trigger this. Research shows that without adequate male evaluation, couples can end up pursuing unnecessary, costly, and invasive treatments for the female partner when the underlying cause lies with the male.

Where Does Pregnancy Testing Fit In?

While you're working through the fertility evaluation process, tracking ovulation and knowing when to take a pregnancy test remains important every cycle. If male factor issues are being addressed whether through varicocele repair, hormonal treatment, or lifestyle changes, sperm quality can improve meaningfully over a few months.

During that time, timing intercourse correctly and using a sensitive early pregnancy detection test gives you the clearest possible picture of whether conception has occurred. Test at least 12–14 days after ovulation, using first morning urine, for the most accurate result. If you get a negative but your period doesn't arrive, retest 48–72 hours later.

Every cycle is an opportunity. And the earlier you have accurate information, about your fertility and about a potential pregnancy, the sooner you can take the next right step together.

Frequently Asked Questions

What is the most common cause of male infertility? 

Varicocele, abnormally enlarged veins in the scrotum, is the most common correctable cause of male infertility, found in approximately 40% of men with primary infertility. Overall, idiopathic (unexplained) male infertility accounts for up to 44% of cases, often involving subtle hormonal or genetic factors.

Can male infertility be treated? 

Many causes are treatable. Varicocele can be surgically repaired. Hormonal imbalances can be addressed with medication. Obstructive azoospermia may be resolved with surgical sperm retrieval. Lifestyle-related sperm damage is often reversible within 3 months of changes. Non-obstructive azoospermia is the most challenging, but assisted reproductive technologies now give many of these men a path to biological parenthood.

How long does it take to see improvement in sperm quality after lifestyle changes?

Sperm take approximately 74 days to develop from start to finish. This means lifestyle changes, quitting smoking, reducing alcohol, avoiding heat, losing excess weight and you need around 3 months to show meaningful improvement in semen analysis results.

When should a man see a doctor about fertility? 

Per AUA/ASRM guidelines: after 12 months of trying without success (or 6 months if the female partner is 35+). Sooner if there is a known history of testicular surgery, cancer treatment, infections, or undescended testicles.

Does a normal sperm count mean there are no fertility issues? 

Not necessarily. Sperm count is just one parameter. Motility (how well sperm swim), morphology (shape), and DNA integrity all matter equally. A full semen analysis evaluates all parameters and not just count.

If my partner is pregnant, do I still need testing? 

If you conceived without difficulty, testing is not typically needed. But if conception took longer than expected or there was a history of miscarriage, discussing a semen analysis with your doctor is worthwhile.

 

 

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