Male infertility is caused by a range of factors including low sperm count, poor sperm movement, abnormal sperm shape, hormone imbalances, varicocele, blocked sperm transport, infections, genetic conditions, and lifestyle factors like heat exposure, certain medications, and chronic health conditions.
If you and your partner have been trying to conceive without success, you are not alone. About 1 in 7 couples faces fertility challenges, and male factors contribute to roughly half of all cases. Understanding what is causing the problem is the first step toward finding a path forward.
What Is Male Infertility?
Male infertility means a man has a reduced ability to make his partner pregnant. In most cases, there are no obvious symptoms. You may feel completely healthy, but something in your reproductive system is not working as it should.
The issue is almost always tied to sperm – either how many you produce, how well they move, or what shape they are.
Common Causes of Male Infertility
Low Sperm Count
A sperm count below 15 million sperm per milliliter is considered low. Fewer sperm means a smaller chance of one reaching and fertilizing an egg. Low sperm count is one of the most frequent reasons for male infertility.
Poor Sperm Movement (Motility)
Even if your sperm count is normal, sperm need to swim effectively to reach an egg. If less than 40% of your sperm move properly, fertilization becomes much harder.
Abnormal Sperm Shape (Morphology)
Sperm shape affects how well they can penetrate an egg. Too many oddly shaped sperm – two tails, misshapen heads – reduce the chances of conception.
Varicocele
A varicocele is an enlargement of the veins inside the scrotum. It raises the temperature around the testicles, which directly harms sperm production. It is one of the most common and treatable causes of male infertility.
Hormone Imbalances
Testosterone and other hormones control sperm production. When these are out of balance – due to pituitary disorders, thyroid issues, or other causes – sperm production drops significantly.
Blocked Sperm Transport
Sperm travel through a series of tubes from the testicles to the urethra. A blockage anywhere along that path – from prior infection, surgery, or a congenital condition – can prevent sperm from reaching semen at all.
Infections
Sexually transmitted infections like gonorrhea or chlamydia can cause scarring and blockages. Mumps contracted after puberty can also damage the testicles and affect sperm production long-term.
Genetics
Conditions like Klinefelter syndrome or Y-chromosome deletions directly affect how sperm develop. These are inherited or occur during development and often require specialist evaluation.
Heat Exposure
Sperm production requires a temperature slightly below core body temperature. Frequent use of hot tubs, long hours working in hot environments, or wearing tight clothing regularly can raise scrotal temperature and reduce sperm quality over time.
Certain Medications
Some medications interfere with sperm production or function. These include anabolic steroids, chemotherapy drugs, certain antibiotics, and some medications used for depression or high blood pressure. Always review your medication list with a specialist.
Chronic Health Conditions
Conditions like diabetes, celiac disease, and autoimmune disorders can indirectly affect sperm count and quality. In some cases, the body even produces antibodies that attack its own sperm.
Age
Male fertility does not have a sharp cutoff like female fertility, but sperm quality – including DNA integrity – does decline gradually after age 40. Older men can still father children, but the risk of taking longer or facing complications increases.
When Should You Seek Help?
If you have been trying to conceive for 12 months without success – or 6 months if your partner is over 35 – it is time to get evaluated. Do not wait. Early diagnosis gives you more options and a better chance of a positive outcome.
You should also seek help sooner if you have a known history of testicular injury, prior infections, surgeries in the pelvic area, or a family history of fertility issues.
How Is Male Infertility Diagnosed?
Diagnosis typically starts with a semen analysis – a lab test that measures sperm count, movement, and shape. A provider may also order hormone blood tests, a physical exam, or imaging to check for varicocele or blockages.
A single test result is not always definitive. Sperm quality can vary, so more than one analysis is often done before drawing conclusions.
Why Getting Evaluated Early Matters
Waiting months before seeking answers is one of the most common – and costly – mistakes couples make. Small problems caught early are almost always simpler and less expensive to address than conditions left to progress, a point often emphasized by Dr Nudell.
A man with a treatable varicocele who gets it addressed early may avoid years of frustration. A man who delays and develops secondary complications faces a longer road.