Male Fertility Explained — What Sperm Count Actually Tells You

When people talk about male fertility, they almost always talk about sperm count. Count is the number that gets cited in conversations, the number that generates anxiety, and the number that most men focus on when they eventually get a semen analysis.

Count matters. But it is one of three primary parameters in a semen analysis — and not always the most clinically important one. Understanding all three, what they mean individually, and what they mean together gives you a genuinely useful picture of male fertility rather than a partial one.

The Three Primary Parameters

1. Sperm Count

Sperm count refers to the number of sperm present in a semen sample, measured as the concentration (sperm per millilitre) and the total count (sperm in the whole sample).

The WHO reference values (2021) define normal as:

• Concentration: ≥16 million sperm per millilitre
• Total count: ≥39 million sperm per ejaculate

Below these thresholds, the clinical terms used are:

• Oligospermia: Low count (below the threshold)
• Cryptozoospermia: Very few sperm, requiring careful laboratory searching
• Azoospermia: No sperm in the ejaculate

A low count reduces the probability of natural conception but does not make it impossible. The severity of the reduction matters — mildly low count is a different clinical picture from severely low count.

2. Sperm Motility

Motility refers to the ability of sperm to move — and specifically, to move in the right way. A semen analysis distinguishes between:

• Progressive motility: Sperm moving in a straight or large-curve pattern (the kind that actually reaches the egg)
• Non-progressive motility: Sperm moving but not in a useful direction
• Immotility: Sperm not moving at all

The WHO reference value for total motility is ≥42%, and for progressive motility ≥30%.

Low motility — called asthenozoospermia — is clinically significant because even a high sperm count has limited fertility value if the sperm cannot swim effectively to reach the egg.

This is one reason why motility is often considered more functionally important than count. A man with a count of 25 million and 15% progressive motility is in a worse fertility position than a man with a count of 18 million and 50% progressive motility.

3. Sperm Morphology

Morphology refers to the shape and structure of sperm. A normal sperm has a smooth oval head, no structural defects in the midpiece, and a straight tail. Abnormal morphology includes sperm with misshapen heads, broken midpieces, or coiled tails.

The WHO reference value for normal morphology (Kruger strict criteria) is ≥4%. This threshold may seem surprisingly low — it reflects the fact that a majority of sperm in any sample have some morphological irregularity, and only a small percentage need to be structurally normal.

Low morphology — called teratozoospermia — is associated with lower fertilisation rates both in natural conception and in IVF (though less so in ICSI, where a single sperm is selected and injected directly into the egg).

What the Results Mean Together

The most useful reading of a semen analysis is not any single parameter in isolation — it is the combination.

| Situation | Clinical implication | |---|---| | Normal count, low motility | Motility is the primary barrier; natural conception is possible but reduced | | Low count, normal motility + morphology | Count-specific treatment may help (IUI, IVF) | | Low count + low motility | Combined factor; IVF with ICSI is more likely needed | | All parameters low | Significant male factor; specialist review essential | | All parameters normal | Standard male fertility picture; other causes of difficulty should be investigated |

What a Semen Analysis Does Not Measure

A standard semen analysis tells you about count, motility, and morphology. It does not tell you everything about male fertility. The most clinically significant gap:

Sperm DNA fragmentation. This refers to damage to the genetic material inside sperm. High DNA fragmentation is associated with longer time to conception, higher miscarriage rates, and lower IVF success rates — even when count, motility, and morphology appear normal.

DNA fragmentation testing is a separate test. It is not part of a standard semen analysis. For men over 35, or where a couple has experienced recurrent miscarriage, or where IVF cycles have produced embryos of unexpectedly poor quality, DNA fragmentation testing adds important information.

Hormonal status. Testosterone, FSH, and LH levels help assess whether a low count has a hormonal cause that may be addressable. These require a separate blood test.

What Causes Abnormal Semen Parameters?

The most common causes include:

• Varicocele: Varicose veins around the testis that raise scrotal temperature and impair sperm production. A common cause of male factor, and surgically correctable.
• Previous infection: Sexually transmitted infections (particularly chlamydia) can damage the epididymis or vas deferens.
• Hormonal imbalance: Low testosterone, elevated FSH, or disorders of the pituitary gland.
• Lifestyle factors: Smoking, alcohol, heat exposure (frequent saunas, tight clothing), and anabolic steroids all affect sperm parameters.
• Idiopathic: In many cases, no cause is found. Parameters can still be improved with lifestyle optimisation in this group.

What to Do After an Abnormal Result

An abnormal semen analysis is the beginning of an investigation, not the end of it. The next steps typically include:

1. Repeat the test after 70–90 days (the full cycle of sperm production). Parameters can vary between samples, and lifestyle changes made now will show up in results three months later.
2. Hormonal blood panel: Testosterone, FSH, LH, prolactin — to identify any hormonal cause.
3. Specialist review: A urologist or andrologist with fertility expertise can assess for varicocele and other structural causes.
4. Lifestyle review: Smoking, alcohol, heat, supplements, and anabolic steroid use all affect parameters and should be addressed.

A free fertility assessment helps both partners understand their fertility picture together — including what a semen analysis result means in the context of the female partner's investigations, and what the most useful next steps are.

Sperm count is part of the picture. The full picture is what lets you make the right decisions.