If you have been trying to conceive for a while, there is a good chance most of the testing so far has landed on one person. Cycle tracking, bloodwork, ultrasounds, maybe a dye test of the tubes. The other half of the equation often gets checked months later, if at all.
That order does not match the biology. Professional guidance in reproductive medicine consistently describes male factors as contributing to a substantial share of infertility, commonly described as around half of cases, either alone or alongside a female factor. And the first test for male fertility is among the simplest and least invasive in the entire workup.
Here is what a semen analysis measures, why those numbers are easy to misread, and which lifestyle factors have real evidence behind them. This is general education, not diagnosis. Only a qualified clinician who knows your history can interpret your results.
What a semen analysis actually measures
A semen analysis is not a single score. It is a panel of separate measurements that can move independently. Someone can have a high count with poor motility, or excellent motility with low volume.
- Volume. How much fluid is in the sample. Most of it comes from the seminal vesicles and prostate rather than the testes, so low volume often says more about the plumbing or the collection than about sperm production.
- Concentration. How many sperm per milliliter. This is the number people usually mean by "count."
- Total sperm number. Concentration multiplied by volume. Many clinicians find this more meaningful, since a small sample can look concentrated while containing few sperm overall.
- Total motility. The percentage of sperm moving at all, in any fashion.
- Progressive motility. The percentage moving forward in a purposeful, roughly straight line. This one matters a great deal, because sperm that wiggle in place are not traveling anywhere useful.
- Morphology. The percentage with a normally shaped head, midpiece, and tail under strict criteria.
Your report may also list vitality, pH, liquefaction time, clumping, and white blood cells that can suggest infection. If those lines confuse you, they are worth asking about.
How reference values really work
This is the single most useful thing to understand about the report you get back.
Reference values are not a pass or fail grade. They are drawn from the lower end of the distribution, roughly the bottom few percent, of men whose partners conceived naturally within about a year. By definition, then, a small share of men with proven fertility falls below any given threshold.
A result flagged as low does not mean conception is off the table, and a result inside the range does not guarantee anything. These are population statistics used to sort people toward more or less investigation, not verdicts about an individual.
This article deliberately does not print a table of cut-offs. The specific lower reference limits have been revised across editions of the WHO laboratory manual, and labs differ in which edition they report against and in their methods. Compare your results against the reference range printed on your own report, and ask the clinician who ordered the test which standard the lab used and what your numbers mean in your situation.
One point does surprise almost everyone. Under strict morphology criteria the threshold for normal shape is a low single digit percentage, so it is entirely expected for the large majority of sperm in a fertile man's sample to be judged abnormally shaped. Morphology is also the most subjective parameter and varies between labs and between observers, so many providers weigh it less heavily than motility and total sperm number.
One result is not a diagnosis
Semen parameters vary substantially in the same person from week to week. A recent fever, a stressful stretch, an unusual abstinence window, an incomplete collection, or a sample that sat too long before analysis can all shift the numbers.
An abnormal result is therefore usually repeated before anyone draws conclusions. Labs ask for a specific abstinence window beforehand, commonly a few days, since both much shorter and much longer intervals can distort results. Follow the instructions your lab gives you. If part of the sample was lost, or it traveled a long way to the lab, say so.
Spermatogenesis takes months, not days
Sperm are not stored up from adolescence. They are manufactured continuously, and the process takes time. Development inside the testis takes roughly two to two and a half months by most estimates, followed by a further stretch of maturation in the epididymis, where sperm gain the ability to swim.
Add it up, and the sperm in today's sample began forming roughly two to three months ago.
That single fact reframes almost every question men ask about lifestyle:
- A change you make this week will not show up next week. Retesting is generally most informative after a full production cycle has passed, on the order of three months, and your clinician will advise on timing.
- An unusually poor result may reflect something months earlier, such as a high fever or a very hard training block, rather than anything happening now.
- Because production is ongoing, the system can also respond when a genuine stressor is removed. No change guarantees a different result, but the biology is not frozen in place.
If you already log cycles or treatment details in EggWise, noting the date of a semen analysis alongside any illness or major change makes that months-long lookback easier to reconstruct. Tracking is a record keeping aid for you and your clinical team, nothing more; it does not act on sperm health.
Lifestyle factors, honestly weighed
Some factors here have solid evidence, some are only suggestive, and any single change usually has a modest effect at best. Several sensible changes together are a more reasonable approach than fixating on one. None of it guarantees a particular result, and a great deal of infertility has nothing to do with anything either partner did or did not do.
Heat
The testes sit outside the body for a reason: spermatogenesis works best a few degrees below core temperature. Research links regular hot tub and sauna use, prolonged laptop use on the lap, heated seats, and some occupational heat exposures to reduced sperm parameters. This can be reversible once the exposure stops, though it takes a full production cycle before any change would be visible on a test. Underwear style shows a smaller and less consistent effect.
Smoking, vaping, and cannabis
Tobacco smoking is one of the better established negatives, associated with lower count, reduced motility, and increased sperm DNA damage. Cannabis is associated with reduced concentration and altered motility in a number of studies. Data on vaping is thinner, but there is no reason to assume it is neutral.
Alcohol
Heavy, chronic drinking is consistently associated with poorer semen parameters and lower testosterone. Light to moderate drinking has produced mixed findings. Many providers suggest reducing intake while trying to conceive rather than framing it as all or nothing; your own clinician can advise on what makes sense for you.
Weight and metabolic health
Obesity is associated with lower sperm concentration and motility, and with hormonal shifts including increased conversion of testosterone to estrogen in fat tissue. Insulin resistance belongs to the same picture. Where weight is relevant, gradual and sustainable change is what clinicians tend to discuss, and it is one factor among many rather than a verdict on anyone.
Sleep, stress, and exercise
Short sleep, irregular schedules, and shift work have been associated with lower semen quality in observational research, as has chronic stress, though stress is hard to separate from the sleep and behavior changes that accompany it. To be clear about what that does not mean: stress is not established as a cause of infertility, and no one should be told that relaxing would fix this. Trying to conceive is stressful in itself, which makes the arrow easy to point the wrong way.
Moderate regular exercise generally looks favorable. The concerns sit at the extremes: very high volume endurance training and prolonged intensive cycling have been linked to reduced parameters, likely through heat, pressure, and hormonal effects.
Medications and substances worth flagging
- Testosterone therapy and anabolic steroids. Supplemental testosterone signals the brain to stop driving sperm production and can reduce counts dramatically, sometimes to zero. This surprises many men who assume more testosterone means more fertility. Tell your fertility clinician right away if you take it, and do not adjust or stop it on your own.
- Finasteride and other hormonally active agents, which have been reported to affect semen parameters in some men.
- Certain antibiotics, antifungals, chemotherapy drugs, sulfasalazine, opioids, and some antidepressants, depending on the drug and the dose.
Bring a complete list of everything you take, including over the counter products, gym supplements, and anything ordered online. Never start, stop, or change the dose of a medication, and do not add a supplement, on the basis of an article. That is a conversation with the clinician who prescribes for you.
Varicocele
A varicocele is an enlargement of the veins draining the testicle, similar in concept to a varicose vein. It is common, frequently painless, and often found on exam or ultrasound. It is also one of the more common identifiable and potentially correctable contributors to male infertility.
Not every varicocele needs treatment. Urologists generally consider repair when a clinically detectable varicocele appears alongside abnormal semen parameters and difficulty conceiving. This is not something to diagnose yourself from a description; a reproductive urologist can examine you and weigh the options with you.
A word on DNA fragmentation
A standard semen analysis counts sperm and grades how they move and look, but says nothing about the genetic material inside them. Sperm DNA fragmentation testing attempts to measure that, reporting the share of sperm carrying breaks in their DNA strands.
Higher fragmentation has been associated with lower fertilization and pregnancy rates and with recurrent pregnancy loss. It is not a routine first line test, though. Professional guidance has generally described the evidence as limited and the assays as not fully standardized, with no single agreed threshold for action. It tends to come up in unexplained infertility, recurrent miscarriage, or repeated failed cycles. Treat it as a specialist conversation, not a test to order for reassurance.
Getting tested early, not last
Couples still routinely spend many months on investigation of the female partner before anyone requests a semen analysis. Guidelines generally point the other way: both partners are usually evaluated at the same time, from the start. The test is among the least invasive parts of a fertility workup and carries essentially no physical risk.
Testing early can surface a treatable issue before months slip by, can inform the plan your clinical team recommends (significant male factor may shift the conversation toward ICSI rather than IUI, which is a decision for your team, not an article), and shares the emotional weight more fairly, which matters more than people expect.
Two things worth saying plainly. A normal semen analysis does not rule out every male factor, and an abnormal one is not a statement about anyone's worth or masculinity. Even azoospermia, meaning no sperm found in the sample, has recognized next steps, which can include surgical sperm retrieval in some situations, and a specialist can explain what does and does not apply to you.
When to talk to a clinician
Consider requesting a semen analysis and male fertility evaluation if any of these apply. If you are unsure whether something on this list fits you, that itself is a good reason to ask.
- You have been trying to conceive for 12 months, or 6 months if the female partner is over 35. Both partners should be evaluated at the same time, not in sequence.
- You are about to start IUI or IVF and no recent semen analysis has been done.
- You take, or have ever taken, testosterone, anabolic steroids, or SARMs.
- You have a history of undescended testicle, testicular torsion or trauma, mumps after puberty, hernia repair, or chemotherapy or radiation.
- You notice a lump, swelling, persistent ache, or a mass that feels like a bag of worms in the scrotum. Any new testicular lump warrants prompt medical evaluation on its own terms, separately from fertility.
- You have low libido, erectile or ejaculatory difficulty, reduced facial or body hair, or breast tissue changes, any of which can point to a hormonal cause worth investigating.
- Your report shows very low or zero sperm, or two abnormal results several weeks apart. Ask about referral to a reproductive urologist rather than repeating tests indefinitely.
- You have had recurrent pregnancy loss or cycles that failed to fertilize.
You do not need anything figured out before you book. Bring your medication list, a rough timeline of how long you have been trying, and any past results, and let a qualified clinician take it from there. Nothing in this article is a substitute for advice from someone who can examine you and read your actual results.