Male Fertility · June 2026 · 6 min read
Male fertility is involved in roughly half of all fertility cases — and yet it's still often investigated last. A clearer look at what testing actually shows and why it matters from the start.
The World Health Organization estimates that male factor contributes to around 50% of cases of difficulty conceiving — either as the primary cause or as a contributing one. NICE guidance recommends that both partners are assessed at the same time when investigating fertility, yet many couples still arrive at our clinic having only had the woman tested.
Investigating both partners from the start saves time, money and a great deal of unnecessary worry.
A semen analysis is a simple, non-invasive test. It is the single most useful piece of information about male fertility. The current WHO reference values (6th edition, 2021) look at, among other things:
Concentration — how many sperm per millilitre of semen. The lower reference limit is around 16 million per millilitre.
Total motility — what proportion of sperm are moving. Around 42% or more is considered within normal range.
Morphology — what proportion are a normal shape. Around 4% or more is the current reference value.
It's worth saying clearly: being below a reference value does not mean a man cannot father a child. It means the picture is more nuanced, and worth understanding.
Sperm are produced continuously, and a full production cycle takes roughly 72 to 90 days. That means lifestyle changes made today show up in a semen analysis around three months later. Things that meaningfully influence sperm quality include:
smoking and recreational drug use; high or sustained alcohol intake; weight (both significantly under- and over-weight); heat exposure (saunas, hot tubs, laptops on the lap); some prescribed medications; and untreated infections.
NICE recommends fertility assessment after 12 months of trying to conceive without success, or earlier if there are known risk factors — previous chemotherapy, undescended testes, mumps as an adult, or any history of testicular surgery. If you're in your late thirties or beyond, six months is a reasonable point to seek advice.
A single semen analysis is rarely the whole story. We typically repeat the test after 4 to 12 weeks before drawing conclusions, and we look at it alongside hormone tests, lifestyle factors and medical history. In many cases, sensible changes and targeted treatment make a measurable difference. Where treatment is needed, techniques like ICSI mean that even very low sperm counts are no longer the barrier they once were.
