You can’t know for certain whether you’re infertile without medical testing, but there are signs that suggest it’s worth getting checked. The most obvious one: you and your partner have been having regular unprotected sex for a year without a pregnancy. If your partner is over 35, that window shortens to six months. Beyond that timeline, there are physical symptoms, hormonal clues, and lifestyle risk factors that can point toward a fertility problem before you ever see a specialist.
The Clearest Sign Is Time
Male infertility rarely announces itself with dramatic symptoms. For most men, the first and only indication is that pregnancy isn’t happening. The general guideline is straightforward: if you’ve been trying for 12 months with no success, it’s time for both partners to be evaluated. That timeline drops to six months when the partner with ovaries is older than 35, because egg quality declines with age and delays in diagnosis cost more time.
There are also reasons to skip the waiting period entirely. If you’re over 50, have a known genital abnormality, a history of sexually transmitted infections, ejaculation problems, prior pelvic or abdominal surgery, or a previous diagnosis of infertility, seeing a specialist sooner makes sense.
Physical Signs You Might Notice
Some fertility problems do produce physical clues, though many men overlook them or assume they’re unrelated.
A varicocele, which is an enlarged vein in the scrotum, is one of the most common treatable causes of male infertility. A large varicocele can feel like a “bag of worms” above the testicle and is sometimes visible. Smaller ones are only noticeable by touch. You might also notice that one testicle is smaller than the other, or feel a dull ache in the scrotum that worsens when standing and improves when lying down. Varicoceles don’t always cause infertility, but they’re worth mentioning to a doctor if you’re having trouble conceiving.
Testicle size matters more broadly, too. Unusually small or soft testicles can indicate reduced sperm production, even without a varicocele. Pain, swelling, or lumps in the testicles are also worth investigating, though they may point to other conditions rather than infertility specifically.
Hormonal Clues That Affect Fertility
Testosterone and other reproductive hormones directly control sperm production. When those hormones are out of balance, the effects often show up in ways that seem unrelated to fertility.
A noticeable drop in sex drive is one of the most common signs. While stress, sleep, and relationship dynamics all influence libido, persistently low interest in sex can reflect low testosterone. Difficulty getting or maintaining erections is another signal, particularly when it’s a newer problem without an obvious cause like medication or stress.
Gynecomastia, the development of enlarged or tender breast tissue, happens when the balance between testosterone and estrogen shifts. If you’ve noticed swelling or sensitivity in your chest area alongside other symptoms, that pattern suggests a hormonal issue worth testing. Some men also experience unusual fatigue, loss of muscle mass, or mood changes tied to the same imbalance.
Medications and Substances That Impair Sperm
Several common medications can reduce sperm count or motility, sometimes without your doctor explicitly flagging the fertility risk. These include finasteride (used for hair loss and enlarged prostate), alpha blockers for urinary symptoms, certain antidepressants (SSRIs in particular), anti-epilepsy drugs, and antiretrovirals. Chemotherapy drugs have the most severe impact, often dramatically reducing or eliminating sperm production.
Anabolic steroids deserve special mention because the effect is both common and widely misunderstood. Testosterone supplementation or steroid use sends a signal to the brain that shuts down natural sperm production. Many men using these substances have very low sperm counts or no sperm at all, even while feeling otherwise healthy and strong. The good news is that sperm production often recovers after stopping, though it can take months to a year or more.
Lifestyle Factors That Lower Sperm Quality
Your daily habits have a measurable effect on sperm production, and these are often the most actionable things you can change.
Obesity impairs fertility through multiple pathways. Fat accumulation around the groin raises scrotal temperature, which directly reduces sperm concentration and motility. Excess weight also increases oxidative stress and causes changes to how genes in sperm are expressed, which can lower pregnancy rates. A meta-analysis of nearly 6,000 men found that smoking is associated with reduced sperm count and motility, with the damage proportional to how many cigarettes per day and how many years someone has smoked.
Heat exposure is a surprisingly potent factor. Even a modest scrotal temperature increase of 1 to 1.5°C can impair sperm production and cause abnormal sperm shape. This applies to occupational heat (welding, baking, kitchen work, dry cleaning) but also to everyday habits like frequent hot tub use, keeping a laptop on your lap, or prolonged sitting. The testicles hang outside the body for a reason: they need to stay slightly cooler than core body temperature to produce healthy sperm.
What Testing Looks Like
The first and most important test is a semen analysis. You’ll provide a sample, typically through masturbation at a clinic or at home with a collection kit, and a lab evaluates sperm count, how well the sperm move, and their shape. Because sperm quality fluctuates naturally, doctors recommend at least two analyses spaced about a month apart before drawing conclusions. A single abnormal result doesn’t necessarily mean you’re infertile.
If semen results are abnormal, or if there are signs pointing to a hormonal issue, blood work comes next. Testosterone levels are measured from a morning blood draw (between 8 and 10 a.m., when levels are highest). A total testosterone below 300 ng/dL triggers follow-up testing of free testosterone, along with hormones that regulate the entire system. Follicle-stimulating hormone (FSH) is particularly telling: even when it falls within the normal lab range, a level above roughly 7.6 mIU/mL can signal that sperm production is struggling.
In specific situations, additional tests may be needed. If you produce little or no fluid at ejaculation, a post-ejaculation urine test can check whether sperm are traveling backward into the bladder, a condition called retrograde ejaculation that’s more common in men with diabetes or nerve injuries. A scrotal ultrasound isn’t routine but may be used to confirm a varicocele before treatment or when a physical exam is difficult.
Genetic Conditions That Affect Fertility
Some men have a genetic basis for infertility that they may not discover until they try to conceive. Klinefelter syndrome is the most common, affecting roughly 1 in 500 to 1 in 1,000 men. It results from an extra X chromosome (XXY instead of XY) and often leads to smaller testicles, reduced testosterone, and very low or absent sperm counts. Many men with Klinefelter syndrome are never diagnosed until a fertility workup, because the symptoms can be subtle, especially in the mosaic form where only some cells carry the extra chromosome.
Diagnosis involves a chromosomal analysis from a blood sample, where at least 20 cells are examined for abnormalities. If mosaicism is suspected based on hormone levels or physical findings, more cells are analyzed. Mutations in the gene responsible for cystic fibrosis can also cause male infertility by affecting the tubes that carry sperm, sometimes even in men who have no lung symptoms. Genetic testing is typically recommended when sperm counts are extremely low or when no sperm are found in the ejaculate.
What an Abnormal Result Actually Means
An abnormal semen analysis does not mean you cannot have children. Fertility exists on a spectrum. Men with lower-than-average sperm counts conceive naturally all the time; it may just take longer. The clinical significance increases when multiple parameters are abnormal simultaneously, such as low count combined with poor motility and abnormal shape.
Azoospermia, the complete absence of sperm in the ejaculate, is the most serious finding and requires further investigation to determine whether it’s caused by a production problem in the testicles or a blockage preventing sperm from reaching the ejaculate. Even in azoospermia, sperm can sometimes be retrieved directly from the testicle for use in assisted reproduction. The path forward depends heavily on the underlying cause, which is why a specialist evaluation matters more than any single test number.