What actually affects male fertility?
Male fertility depends mainly on three things: how many sperm are produced, how well they move, and how normally they are shaped — all checked together in a semen analysis. It also depends on hormone levels, the health of the tubes that carry sperm from the testes, and general health factors like weight, smoking, and heat exposure. When a couple sees a fertility specialist, a sperm-related factor is found in a substantial share of cases, either on its own or alongside a female-factor issue. Male fertility isn't reducible to one number on a lab report — it's the combined result of several systems working correctly together.
Sperm are made continuously in the testes in a cycle that takes around three months from start to finish, which is why a change today — a new medication, an illness, a lifestyle shift — doesn't show up on a semen analysis for a few months. This also means many causes of reduced fertility are temporary and can improve once the underlying issue is addressed. Other causes, like blocked tubes or certain genetic conditions, are structural and need medical evaluation rather than lifestyle changes. Because the picture is rarely one single cause, a full work-up usually looks at hormones, anatomy, and semen quality together, rather than assuming any one factor explains everything.
What does a semen analysis actually measure?
A semen analysis measures sperm count (how many sperm are in a sample), motility (the percentage moving well enough to reach an egg), and morphology (the percentage with a typical shape), along with semen volume and a few other markers. Results are compared against standard reference ranges, and a result below the range doesn't mean pregnancy is impossible — it means the odds in any given cycle are lower and worth discussing with a doctor. Because sperm counts naturally vary from sample to sample and even day to day, providers usually ask for two separate tests a few weeks apart before drawing any conclusions. One low result on its own is common and rarely a diagnosis by itself.
The table below shows the general pattern used to interpret a semen analysis. It's meant as a starting point for a conversation with your provider, not a way to self-diagnose from home. Many people with results below these ranges still conceive, sometimes without treatment, and many people with results inside the typical range take longer than expected for entirely unrelated reasons. If your results come back outside the typical range, the usual next step is simply to repeat the test and talk it through with a doctor, not to assume the worst.
| Measure | What it means | Typical reference range* | |---|---|---| | Sperm concentration | Sperm per millilitre of semen | Around 15 million/mL or more | | Total motility | Percentage of sperm moving | Around 40% or more | | Morphology | Percentage with a typical shape | Around 4% or more | | Semen volume | Amount of semen per sample | Around 1.5 mL or more | *Reference ranges vary by lab — ask your provider to explain your specific results rather than comparing them to a general chart.
Does male age affect fertility too?
Yes — sperm quality and count both decline with age, though the change is slower and more gradual than the typical female pattern, and there's no single age where male fertility drops sharply. From around the mid-40s, many providers start to see measurable declines in motility and morphology, along with a modest rise in DNA fragmentation, which is damage to the genetic material inside sperm. Older paternal age has also been linked to a small increase in certain conditions in offspring. Male fertility doesn't disappear with age, but it isn't unaffected by it either, and it can matter more when a partner is also older.
Because sperm production continues throughout life, age-related decline in men is far less predictable than the fixed, diminishing egg supply that drives female fertility decline. Two men of the same age can have very different semen analysis results depending on health, lifestyle, and genetics. This is part of why couples where both partners are older are sometimes advised to seek evaluation sooner than either age alone would suggest — the effects can add up rather than simply average out. If you're an older father-to-be and have concerns, raising them with a doctor is reasonable and doesn't need to wait until months of trying have passed.
What lifestyle factors can lower sperm quality?
Smoking, heavy alcohol use, being significantly over or under a healthy weight, and anabolic steroid use are among the lifestyle factors most consistently linked to lower sperm count and motility. Prolonged heat exposure — frequent hot tub or sauna use, tight underwear, or a laptop resting directly on the lap for long stretches — can also reduce sperm quality, since the testes function best slightly cooler than body temperature. Recreational drug use has also been associated with lower sperm counts in some studies. None of these factors guarantee infertility on their own, but each is a modifiable piece of the picture worth addressing if you're trying to conceive.
Because sperm take around three months to develop, the benefits of a lifestyle change — quitting smoking, cutting back on alcohol, losing excess weight, avoiding prolonged heat — typically take about that long to show up in a semen analysis. This is worth knowing so you don't judge a change too early or assume it hasn't worked after only a few weeks. Stress and poor sleep are also commonly discussed, though their direct effect on sperm parameters is less clearly established than factors like smoking or heat. Addressing what you can control is reasonable and often helpful, but it isn't a guarantee of a particular result.
What medical conditions or medications can affect male fertility?
A varicocele — enlarged veins in the scrotum, similar to varicose veins — is one of the most common treatable causes of reduced sperm quality, and it's often found on physical exam. Hormonal conditions affecting testosterone or the pituitary gland, past infections like mumps after puberty, undescended testicles in childhood, and certain genetic conditions can all reduce sperm production. Some medications — including certain blood pressure drugs, some antidepressants, testosterone replacement therapy, and some chemotherapy drugs — can lower sperm count or motility as a side effect. If you're taking a regular medication and trying to conceive, ask your prescribing doctor whether it could be a factor rather than stopping it on your own.
Certain symptoms are worth mentioning to a doctor promptly rather than waiting: a new lump, swelling, or persistent pain in the testicles, a history of undescended testicle, previous groin or testicular surgery, or signs of a hormonal problem such as low sex drive, unexplained fatigue, or breast tenderness. These don't automatically mean infertility, but they're the kind of findings a doctor can evaluate quickly, often with a simple exam and blood test. Testicular pain or a new lump specifically should be checked the same week rather than left to see if it resolves on its own.
When should you get tested or see a doctor?
The standard guidance is that if you and your partner have been trying for 12 months without success — or 6 months if she's 35 or older — it's worth both partners getting evaluated, and a semen analysis is usually one of the first and simplest tests offered. If you already know about a risk factor — a past varicocele, undescended testicle, prior chemotherapy, or a hormonal condition — there's no reason to wait for the full 12 months before asking for testing. A semen analysis is inexpensive, non-invasive, and gives useful information regardless of when in the process you get it done.
Our guide to [fertility evaluation](/getting-pregnant/fertility-evaluation) walks through what a first fertility visit for either partner typically involves. If you notice testicular pain, a new lump, or swelling, don't wait for a fertility check-up — see a doctor promptly, since these can have causes unrelated to fertility that also need attention. Anxiety about male fertility is common and understandable, and naming it to a doctor directly, rather than guessing from general information, is usually the fastest way to get a real answer for your situation.
What can you do to support male fertility?
Maintaining a healthy weight, not smoking, limiting alcohol, avoiding prolonged heat exposure, and managing conditions like diabetes or high blood pressure are the main modifiable factors that support sperm quality at any age. Since sperm take about three months to develop, give any change at least that long before expecting to see a difference on a repeat semen analysis. A varied diet with adequate antioxidants, vitamins, and minerals is often recommended, though evidence for specific supplements improving pregnancy rates is mixed, and a doctor can advise on what's actually worth trying for you. None of these steps guarantee a particular outcome, but they remove some of the barriers that can be addressed.
Tools like babybumpkit's [ovulation calculator](/ovulation-calculator) and [conception calculator](/conception-calculator) can help make the most of the fertile window each cycle, which matters for both partners regardless of semen quality. If a semen analysis does find an issue, treatments range from simple lifestyle changes and surgery for a varicocele to IUI or IVF with or without additional sperm-selection techniques, and success rates vary by cause and by clinic. Your doctor or a reproductive urologist can explain what's realistic for your specific results, which a general article like this one can't do on its own.