You can’t know for certain whether you’re infertile without a medical evaluation, but there are signs that suggest a problem worth investigating. The clinical threshold is straightforward: if you and your partner have been having regular unprotected sex for 12 months without a pregnancy (or 6 months if she’s 35 or older), that meets the medical definition of infertility. About half of all infertility cases involve a male factor, so getting checked early matters.
That said, some men notice warning signs well before they start trying to conceive. Here’s what to look for and what happens when you get tested.
Physical Signs That May Point to a Problem
Most men with fertility issues have no obvious symptoms at all. Their sex life feels normal, and nothing seems visibly wrong. But when symptoms do appear, they tend to fall into a few categories.
Sexual function changes are among the most noticeable. Difficulty maintaining an erection, reduced sex drive, trouble with ejaculation, or producing very little fluid when you ejaculate can all signal hormonal or structural issues that affect fertility. These don’t guarantee infertility, but they’re worth mentioning to a doctor.
Testicular changes are another red flag. Pain, swelling, or a lump in the testicle area should always be evaluated. Small or unusually soft testicles can indicate reduced sperm production, since the testicles are where sperm is made and stored. If you’ve used anabolic steroids, be aware that they can cause the testicles to shrink and significantly reduce sperm output, sometimes for months or longer after stopping.
Hormonal imbalances sometimes show up in unexpected ways. Abnormal breast tissue growth (called gynecomastia), noticeably decreased facial or body hair, or a loss of muscle mass can reflect low testosterone or other hormonal disruptions tied to fertility. These signs often point to conditions that are treatable once identified.
Varicoceles: The Most Common Treatable Cause
A varicocele is an enlarged vein in the scrotum, similar to a varicose vein in the leg. It’s the single most common identifiable cause of male infertility, found in roughly 17% to 41% of men evaluated for fertility problems. A large European study of nearly 8,000 men referred for infertility found varicoceles in about 17% of them.
You might notice a dull ache in the scrotum that worsens after standing for long periods, or a visible, lumpy mass above one testicle (usually the left). Smaller varicoceles produce no symptoms at all and are only found during a physical exam. They’re graded on a three-point scale: grade one is only detectable when a doctor asks you to bear down, grade two can be felt while standing, and grade three is visible through the skin. Some are so small they only show up on ultrasound.
Varicoceles raise the temperature around the testicles, which impairs sperm production over time. The good news is that surgical correction often improves sperm quality.
Lifestyle Factors That Quietly Reduce Fertility
Even without an underlying medical condition, everyday habits can drag sperm quality down substantially.
Body weight has one of the strongest effects. Men with a BMI outside the normal range (18.5 to 24.9) show significantly worse sperm numbers across the board. In one cross-sectional study, men at a normal weight averaged a sperm concentration of about 95 million per milliliter, while overweight or underweight men averaged around 70 million. Motility (the percentage of sperm that swim properly) dropped from 78% to 61%, and DNA damage in sperm was meaningfully higher in the altered-weight group.
Smoking carries a 2.36-fold increased risk of impaired semen quality, with reductions in sperm concentration, total count, motility, and the percentage of normally shaped sperm. The damage is dose-dependent, meaning heavier smokers tend to see worse results.
Heat exposure is another underestimated factor. Occupational heat (welding, baking, long-haul driving) and recreational heat (frequent hot tub or sauna use, prolonged cycling) raise scrotal temperature enough to damage sperm DNA. One study found that 62% of men with regular heat exposure had elevated sperm DNA fragmentation, compared to 47% of men without that exposure. If you’re trying to conceive, keeping your laptop off your lap and limiting time in hot environments is a simple, low-cost adjustment.
What a Fertility Evaluation Looks Like
The first and most important test is a semen analysis. You provide a sample (usually through masturbation at a clinic or at home with a specific collection kit), and a lab evaluates it against reference values set by the World Health Organization.
The key benchmarks from the WHO’s latest edition are:
- Total sperm count: at least 39 million per ejaculate
- Progressive motility: at least 30% of sperm swimming forward
- Normal morphology: at least 4% of sperm with a normal shape
Falling below any of these doesn’t automatically mean you can’t father a child, but it does lower the odds with each cycle and signals that further investigation is warranted. Because sperm quality fluctuates, doctors typically order two analyses spaced a few weeks apart before drawing conclusions.
If results are abnormal, the next steps usually include a physical exam (checking for varicoceles, testicular size, and anatomical issues), blood work to measure testosterone and other reproductive hormones, and sometimes a scrotal ultrasound. For men with very low sperm counts (under 5 million per milliliter) or no sperm at all, genetic testing is recommended to look for chromosomal abnormalities or Y-chromosome deletions that can cause production to fail.
Are At-Home Sperm Tests Worth It?
If visiting a fertility clinic feels like a big step, at-home sperm tests can serve as a reasonable screening tool. Smartphone-based devices like the YO Home Sperm Test measure motile sperm concentration (the number of moving sperm per milliliter) and have shown strong accuracy when compared to lab-grade analyzers, with a 97.8% accuracy rate and correlation coefficients above 0.92 in validation studies. They’re particularly good at identifying samples that fall below the “low” threshold of 6 million motile sperm per milliliter.
The limitation is scope. A home test tells you whether your motile sperm count is in a low, moderate, or normal range. It doesn’t evaluate morphology, total volume, white blood cell count, or other factors that a full semen analysis covers. Think of it as a first pass. A normal home result is reassuring but not definitive, and a low result should prompt a full clinical workup rather than panic.
When the Cause Isn’t Obvious
In roughly 30% to 40% of male infertility cases, no clear cause is ever identified. Semen parameters are low, but hormone levels look fine, no varicocele is found, and genetic tests come back normal. This is called idiopathic infertility, and while it’s frustrating, it doesn’t mean nothing can be done. Lifestyle optimization (reaching a healthy weight, quitting smoking, reducing heat exposure, managing stress) can improve sperm quality over the course of two to three months, which is roughly how long a new cycle of sperm takes to mature.
For couples where natural conception isn’t happening despite these changes, assisted reproductive options like intrauterine insemination or in vitro fertilization can bypass many of the barriers that low sperm counts or poor motility create. The specific path depends on the severity of the issue and the female partner’s fertility status, which is why both partners are typically evaluated together.