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Male Fertility Explained with Professor Allan Pacey

Male Fertility Explained with Professor Allan Pacey
Authored by
Shaun Greenaway

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Male fertility depends on producing enough functional sperm, delivering them into semen and having sex or treatment that allows sperm to reach an egg. It cannot be judged from appearance, masculinity or sexual performance. A laboratory semen analysis is the usual first test, but the result must be interpreted alongside medical history, examination and the fertility of both partners.

What does male fertility mean?

Male fertility is the ability to contribute to a pregnancy. It involves more than sperm count. The reproductive system must:

  • Produce sperm in the testicles
  • Support production through appropriate hormonal signals
  • Store and transport sperm through the reproductive tract
  • Add seminal fluid and ejaculate it effectively
  • Produce sperm capable of moving towards and fertilising an egg

A problem at any of these stages may reduce the chance of conception. Some causes are identifiable and treatable, while others remain unexplained even after investigation.

Sex drive, erections and ejaculation can affect conception, but they are not measures of sperm quality. A man can have normal sexual function and no sperm in his semen, or have healthy sperm but difficulty with erections or ejaculation.

How do you know whether there may be a male fertility problem?

Most men discover a possible problem only after a couple has difficulty conceiving. Low sperm concentration, poor motility or azoospermia usually has no visible symptom.

You should speak to a GP if you and your partner have not conceived after one year of regular sex without contraception, or after six months if your partner is aged 36 or over. Seek advice sooner if there is a known concern, such as:

  • Previous chemotherapy, radiotherapy or testicular surgery
  • Undescended testicles, testicular injury or infection
  • A testicular lump, swelling or persistent pain
  • Problems with erections or ejaculation
  • Previous abnormal semen-analysis results
  • Use of testosterone or anabolic steroids
  • A genetic or hormonal condition that may affect reproduction

Both partners should be assessed where possible. Fertility is a shared outcome, and investigating only one person can delay useful answers.

What is the main male fertility test?

A diagnostic semen analysis is the usual first-line test. A laboratory examines a fresh semen sample and reports measurements including:

  • Semen volume
  • Sperm concentration and total sperm number
  • Total and progressive motility
  • Morphology, meaning sperm shape under strict criteria
  • Vitality, when needed
  • Other observations such as pH, liquefaction or white blood cells

The 2026 NICE guideline uses lower reference values derived from the World Health Organization laboratory manual. These are not pass-or-fail thresholds. A result below a reference value does not prove infertility, and a result above every value does not guarantee pregnancy.

An abnormal first result should normally be repeated. NICE recommends a confirmatory analysis ideally about three months later, or sooner if no sperm or a severe sperm deficiency is found.

Read Semen Analysis Results Explained for a detailed interpretation guide.

Are sperm counts declining?

A widely discussed 2022 systematic review and meta-regression reported a substantial fall in average sperm concentration and total sperm count in samples collected globally between 1973 and 2018. It also found evidence that the rate of decline was steeper after 2000.

This is important population-level research, but it needs careful interpretation:

  • It does not mean every man’s sperm count is falling
  • It does not identify one proven cause
  • Semen-analysis methods, study populations and geography differ
  • Sperm count is only one part of male fertility
  • Population trends cannot diagnose an individual

Researchers are examining possible contributions from health, lifestyle, obesity, smoking, environmental exposures and endocrine-disrupting chemicals. The decline is a reason to take male reproductive health seriously, not a reason to assume that infertility is inevitable.

How do testosterone and anabolic steroids affect fertility?

Testosterone is essential inside the testicles for sperm production. However, taking testosterone from outside the body can reduce the hormonal signals that stimulate the testicles. Prescription testosterone and anabolic steroids can therefore suppress sperm production, sometimes severely.

This often surprises people because anabolic steroids may increase muscle mass and because testosterone is associated with male sexual characteristics. Higher testosterone in the bloodstream from medication or steroid use does not mean higher sperm production.

Recovery after stopping anabolic steroids or testosterone varies. It can take months, may require specialist management and is not guaranteed to follow the same pattern for every person. Do not stop prescribed treatment without speaking to the responsible clinician.

If you want children now or in the future, tell any clinician prescribing testosterone and be open about non-prescribed steroid use. Ask whether a semen analysis and reproductive hormone tests are appropriate and whether fertility preservation should be discussed before treatment.

Can you improve male fertility through lifestyle?

Lifestyle is relevant to reproductive and general health, but it is not a complete explanation for male infertility and cannot correct every medical, genetic or anatomical cause.

Reasonable steps include:

  • Stop smoking
  • Avoid anabolic steroids and recreational drugs
  • Keep alcohol within the UK guideline of no more than 14 units a week, spread across several days
  • Aim for a healthy weight through a balanced diet and regular activity
  • Discuss occupational exposure to pesticides, solvents or heavy metals
  • Review medication with a clinician rather than stopping it yourself
  • Avoid repeatedly exposing the testicles to excessive heat where practical

Do not promise yourself that three months of supplements will “fix” an abnormal result. The 2026 NICE guideline does not recommend supplements, antioxidants or medical treatments to improve sperm DNA integrity. If a product is suggested, ask whether it improves a semen measurement or has evidence for pregnancy and live birth in people like you.

Read How to Check Your Sperm Health for a practical testing and lifestyle guide.

Are home sperm tests useful?

Home tests are not all the same. Some services allow you to collect at home and send the sample to an andrology laboratory. Many instant kits measure only sperm concentration, motility or another limited marker.

A limited home result cannot rule out a problem with something it does not assess. It may also offer little information about possible causes or next steps. Before buying a test, check:

  • Which semen measurements it reports
  • Whether a suitable laboratory analyses the sample
  • How collection time and temperature are controlled
  • Whether a qualified professional explains the complete result
  • What happens if the result is unusual
  • Whether the service will refer you for clinical assessment

A home test may lower the barrier to checking, but it should not delay speaking to a GP when you meet the criteria for fertility assessment or have symptoms or relevant medical history.

For more detail, read The Growth of Home Sperm Testing.

What further tests might be needed?

Further investigation depends on the semen result, history and examination. It can include:

  • A physical examination of the testicles and scrotum
  • Testosterone and gonadotrophin blood tests
  • Ultrasound when there is a specific indication
  • Genetic tests for particular patterns of azoospermia or severe oligozoospermia
  • Assessment of erections, ejaculation or possible infection

The 2026 NICE guideline says not to carry out sperm DNA-integrity or fragmentation testing as part of fertility investigation. It found uncertainty about the relationship with subfertility, the appropriate test and threshold, and an effective treatment response.

Ask how any proposed test would change your diagnosis or care before paying for it privately.

What can treatment involve?

The appropriate pathway depends on both partners, the cause and severity of any problem, age, preferences and how long you have been trying.

Options may include:

  • Treating an identified hormonal, medical or anatomical cause
  • Timed regular sex or, in selected circumstances, intrauterine insemination
  • IVF or ICSI
  • Surgical sperm retrieval when indicated
  • Donor sperm
  • Fertility preservation before treatment that could damage sperm production

An abnormal semen result does not automatically mean that ICSI is the only option. NICE recommends considering ICSI when semen parameters are abnormal, taking severity into account, or after failed or very low fertilisation in a previous IVF cycle. It says not to use ICSI for non-male-factor fertility problems when semen parameters are normal.

Could sperm be grown in a laboratory in the future?

Researchers are studying in-vitro gametogenesis and ways to create or mature reproductive cells outside the body. The long-term goal could be to help some people who cannot produce usable sperm.

This work remains experimental. Important questions about genetic and epigenetic safety, reliable maturation, regulation and the health of future children must be resolved before any laboratory-grown human sperm could become routine treatment. It should be presented as a research direction, not an option currently available to patients.

Questions to take to a fertility appointment

  • Can both partners be investigated at the same time?
  • Can I have a complete laboratory semen analysis rather than a limited screening test?
  • If the result is abnormal, when will it be repeated?
  • Could testosterone, anabolic steroids, medication or a medical condition be relevant?
  • Do I need a physical examination or hormone tests?
  • Is there a possible underlying cause that should be investigated before treatment?
  • How would any additional test change the plan?
  • What are the alternatives, benefits, limitations and costs of the treatment being proposed?

The most important thing to remember

Male fertility deserves direct investigation, not guesswork or blame. Start with a proper semen analysis and an honest medical history, involve both partners and ask for abnormal results to be confirmed and explained. Lifestyle can support reproductive health, but it should sit alongside appropriate clinical assessment rather than replace it.

The original session with Professor Allan Pacey explores sperm-count trends, anabolic steroids, home testing, future research and practical steps for men. Before publication, any statement presented as Professor Pacey’s view should be checked against the recording and approved by him or his representative.

If the process is affecting your mental health or relationship, you can join The Male Fertility Hub community.

Sources

This article provides general information and does not replace individual medical advice. Speak to your GP or fertility specialist about your circumstances.