What causes infertility in men?

Infertility in men can be caused by a number of factors:
  • Sperm deficiencies can include low sperm production (oligospermia) or lack of sperm (azoospermia).
  • Sperm may also have poor motility. This means that they don't move properly once inside the female reproductive tract to achieve fertilization.
  • Additionally, sperm cells may be malformed or may not survive long enough to reach the egg.
An estimated 20% of all couples' infertility cases are unexplained; the source of the problem cannot be identified. Disorders of both the male and female reproductive systems cause infertility with almost equal frequency. Some infertile couples have more than one factor contributing to their infertility.
There are several causes of male infertility. These causes include physical abnormalities, hormonal imbalance, lifestyle factors, and psychological or behavioral problems. Physical abnormalities include damaged sperm ducts and a condition called varicocele in which veins around one testicle are enlarged. Hormonal imbalances can be due to a thyroid problem or pituitary gland malfunction. Lifestyle factors that reduce fertility include tobacco use, marijuana use, and alcohol abuse. There are several other factors as well. For more information schedule a visit with your doctor.

The three most common causes of male infertility are:

  • the body's inability to make healthy sperm,
  • the body's inability to make a sufficient number of sperm, and
  • the inability of the man's body to transport the sperm to the semen and then out of the body.
There are a variety of medical issues that can cause some or all of these three general problems.
  • The inability to make healthy sperm can be caused by a variety of issues, including a hormonal imbalances, inherited chromosome abnormalities, certain medications, exposure to adverse environmental elements, and other more rare complications.
  • An insufficient number of sperm may be related to many of the issues in the point above, as well as physical problems within the scrotum (such as swelling, physical trauma or immunological issues).
  • Problems delivering the sperm into the woman's body can include swelling and physical trauma, retrograde ejaculation where the sperm are directed into the bladder rather than out of the body, or blockages or sperm duct defects.

A standard set of diagnostic exams are typically sufficient to identify the cause of an individual's male infertility. Once the specific causes are identified, a doctor can then recommend a variety of treatment options.

Infertility in men can be caused by a number of factors including:
  • Genetic: Male infertility can be inherited, especially when
           Y-chromosomes are missing a tiny piece of genetic code. Men
           who have genetic causes of infertility may pass the problem
           to their sons if they are able to father a child through
           infertility treatments.
  • Hormonal: Men whose hormones are out of balance can become
           infertile. This can sometimes be related to cancer or
  • Physical: There may be physical reasons such as problems with
           the tubes that form the pathway for sperm to travel to the
           areas near the prostate. These tubes can be blocked by scar
           tissue after injury or infection. Lower sperm counts can also
           be caused by varicoceles or clusters of enlarged veins in the
  • Disease-related: Some diseases or illnesses can cause lower
           sperm counts such as cancer, diabetes, mumps orchitis or
  • Environmental: Exposure to environmental factors can affect
           fertility such as high heat, radiation or pesticides.
  • Lifestyle factors: Obesity, tobacco use, heavy drinking, or using
           anabolic steroids for body-building can affect fertility.
  • Age: Semen quality may decrease with age.
  • Cancer and treatment for cancer: Some types of cancer
           treatment may interfere with a man's fertility, either
           temporarily or permanently.
Infertility can be classifed as pre-testicular, testicular and post-testicular.  

Pre-testicular means there may be a problem in the hormonal balance in your body because the hypothalamus and pituitary in the brain controls testis sperm and testosterone production. 
Testicular means there is a congenital or acquired reason for the testicles to not produce adequate numbers or normal sperms.

Post-testicular means there is a blockage or problem with the tract that the sperms have to travel from the testis to the tip of the penis, including such issues such as previous vasectomy, hernia surgery, ejaculatory duct obstruction, retrograde ejaculation, etc.

A variety of factors can cause infertility in men. When men are infertile, it means there is a problem with their sperm that makes them unable to fertilize an egg. Sometimes problems in the scrotum or testicles may affect the amount of sperm produced, or it can affect the shape and structure of sperm, making them unable to properly fertilize the egg. Certain genetic conditions or hormone deficiencies can also cause defects in the sperm themselves. Other times, medical and psychological conditions may cause problems with the way sperm is delivered. For instance, things like diabetes or injuries may cause a lack of semen or may interrupt the flow of semen out of the penis. Some cases of infertility in men are caused by environmental or lifestyle factors, including exposure to certain chemicals, stress, smoking, drug or alcohol use, and aging.

Dr. Michael Roizen, MD
Internal Medicine
Many things can cause male infertility. That's because the journey a sperm takes to fertilize an egg isn't as simple as swimming a lap in a pool; it's more like crossing the English Channel without a wetsuit. Lots of things have to go right to get from one shoreline to the other.

There are two common problems:
  1. Low sperm count, which means that without as many swimmers, there's less of a chance one will reach the finish.

  2. Lack of sperm mobility, which means the sperm simply don't have the strength to make the entire journey, and those cells die before they reach the shore.
YOU: The Owner's Manual, Updated and Expanded Edition: An Insider's Guide to the Body that Will Make You Healthier and Younger

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YOU: The Owner's Manual, Updated and Expanded Edition: An Insider's Guide to the Body that Will Make You Healthier and Younger

Between your full-length mirror and high-school biology class, you probably think you know a lot about the human body. While it's true that we live in an age when we're as obsessed with our bodies as...
Kevin W. Windom, MD
OBGYN (Obstetrics & Gynecology)
The most common cause of male infertility is a low sperm count. Some men can have a problem with decreased motility or abnormal morphology(shape) of the sperm. Men can have sperm abnormalities for numerous reasons such as previous injury to the testicles, numerous medical conditions, abnormal male anatomy, or a varicocele (dilated blood vessel around the testicles).  If a man has an abnormal sperm count, I think it is important for him to seek care from an urologist whose specialty is male factor infertility. There are numerous treatments that can be performed that can easily effect the sperm count and remedy male infertility.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.