Infertility Causes – Male

All factors that causes of infertility in men either affect the sperm morphology or mobility.

Sperm abnormalities can be caused by a range of factors, including congenital birth defects, disease, chemical exposure, and lifestyle habits. In many cases, the causes of sperm abnormalities are unknown. Sperm abnormalities are categorized by whether they affect sperm count, sperm movement, or sperm shape. They include:

  • Low Sperm Count (Oligospermia): A sperm count of less than 20 million/mL is considered low sperm. Complete absence of sperm cells is referred to as azoospermia and accounts for 10 - 15% of cases of male infertility. Sperm count varies widely over time, and temporary low counts are common. Therefore, a single test that reports a low count may not be considered for the final decision for treatment.
  • Poor Sperm Motility (Asthenospermia): Sperm motility is the sperm's ability to move. The sperm have difficulty invading the cervical mucous or penetrating the hard outer shell of the egg if movement is slow, not in a straight line, or both. In average quality sperm 60% or more of sperm should have normal motility. Sperm that move sluggishly may have genetic or other defects that make them incapable of fertilizing the egg. Poor sperm motility may be associated with DNA fragmentation and may increase the risk for passing on genetic diseases.
  • Abnormal Sperm Morphology (Teratospermia): Abnormally shaped sperm cannot fertilize an egg. About 60% of the sperm should be normal in size and shape for adequate fertility. The perfect sperm structure is an oval head and long tail.
  • Any structural abnormalities that damage or block the testes, tubes, or other reproductive structures can have a profound effect on fertility. Cryptorchidism is a condition associated with mild to severe impairment of sperm production is usually seen in newborn infants in which the testicles fail to descend from the abdomen into the scrotum. Hypospadias is a birth defect in which the urinary opening is on the underside of the penis, can prevent sperm from reaching the cervix.

Reasons for male infertility:


Age-related sperm changes in men are a gradual process and can adversely affect sperm counts and sperm motility. The genetic quality of sperm declines with age.

Sexually Transmitted Diseases

Infertility may be seen in males with repeated Chlamydia trachomatis or gonorrhea infections. These infections cause scarring and block sperm passage. Human papilloma viruses, the cause of genital warts, may also damage the functions of sperm.

Lifestyle Factors

Sperm count may temporarily get reduced with any major physical or mental stress. Those include; emotional stress, testicular overheating, substance abuse, smoking and bicycling. Certain compounds in marijuana act as receptors for sperms and may impair the sperm's ability to swim and also inhibit their ability to penetrate the egg. Anabolic steroid use can shrink testicles. Smoking and chronic alcohol use-significantly decreases both sperm count and sperm cell motility. Tight underwear increases scrotal temperature which results in decreased sperm production. Inadequate vitamin C and Zinc in the diet, malnutrition or anemia can also be other reasons for infertility. A behavioral modification can improve a man’s fertility and should be considered when a couple is trying to achieve pregnancy.

Hormonal Problems

A small percentage of male infertility is attributed by hormonal problems. The chain of hormonal events regulated by the hypothalamus-pituitary endocrine system enables testes to produce and effectively disseminate sperm. This can be the failure to release gonadotrophic-releasing hormone (GnRH) that causes testosterone synthesis and sperm production or failure to release enough lutenizing hormone (LH) and follicle stimulating hormone (FSH) by the pituitary gland that stimulate the testes and testosterone/sperm production.

  • Hyperprolactinemia: Significantly elevated prolactin reduces sperm production, reduces libido and may cause impotence.
  • Hypothyroidism: Low thyroid hormone levels may decrease semen quality, testicular function and may disturb libido. This may be caused by a diet high in iodine.
  • Congenital Adrenal Hyperplasia: The condition occurs when increased levels of adrenal androgens suppress the pituitary gland function. This can lead to low sperm count, an increased number of immature sperm cells, and low sperm cell motility.
  • Hypogonadotropic Hypopituitarism: Low pituitary gland output of LH and FSH arrests sperm development and causes the progressive loss of germ cells from the testes and deteriorates the seminiferous tubules and Leydig cells.
  • Panhypopituitafism: Complete pituitary gland failure lowers growth hormone, thyroid-stimulating hormone, and LH and FSH levels. This condition leads to lethargy, impotence, decreased libido, loss of secondary sex characteristics, and normal or undersized testicles.

Physical Problems

A variety of physical problems either interfere with the sperm production process or disrupt the pathway down which sperm travel from the testes to the tip of the penis. These problems are usually characterized by a low sperm count and/or abnormal sperm morphology. The following is a list of the most common physical problems that cause male infertility:

  • Varicocele: An abnormally enlarged and twisted vein in the spermatic cord that connects to the testicle is called a varicocele. Damaged spermatic veins cause an abnormal back flow of blood from the abdomen into the scrotum creating a hostile environment for sperm development. Varicoceles are found in 40% of infertile men and 15% of all men. Even though it is unclear how varicoceles affect fertility, it is believed that they can raise testicular temperature. Varicocoeles may cause reduced sperm count and abnormal sperm morphology which cause infertility.
  • Damaged Sperm Ducts: The pathway of sperms from the testicles may get blocked by a number of factors including a genetic or developmental mistake or cause the absence of one or both tubes which transport the sperm from the testes to the penis, scarring from tuberculosis or some STDs may block the epididymis or tubes. Seven percent of infertile men cannot transport sperm from their testicles to out of their penis.
  • Torsion: Is caused by a supportive tissue abnormality which allows the testes to twist inside the scrotum to form extreme swelling. Torsion injures the blood supply to and causes testicular damage. Torsion can seriously impair fertility and cause permanent infertility when both testes twist.
  • Medical Conditions: Medical conditions such as severe surgery diabetes, HIV, thyroid disease, Cushing syndrome, heart attack, liver or kidney failure, and chronic anemia or certain types of medications can affect male fertility by impairing sperm production. Infections like prostatitis (inflammation in the prostate gland), orchitis (in the testicle), semino-vesculitis (in the glands that produce semen), or urethritis (in the urethra), may alter sperm motility. Infections in the testes may leave scar tissue that can block the epididymis. Certain cancers, particularly testicular cancer, severely impair sperm production. Chemotherapy and radiation can damage sperm quality and quantity. The risk for infertility increases with proximity of radiation treatments to the reproductive organs. Problems with the immune system can cause a man's body to treat sperm as if it were a foreign matter. As a result, the immune system may produce antibodies to fight and destroy the sperm. Sexually transmitted diseases or other infections such as chlamydia and gonorrhea can also become one of the causes of infertility in men.
  • Erectile Disfunction (ED): Erectile Disfunction is the result of a single, or more commonly a combination of multiple factors. ED was thought to be the result of psychological problems, but new research indicates that 90 percent of cases are with underlying medical issues. But most men who suffer from ED have a secondary psychological problem that can worsen the situation like performance anxiety, guilt, and low self-esteem. Many of the common causes of impotence include: diabetes, high blood pressure, heart and vascular disease, stress, hormone problems, pelvic surgery, trauma, venous leak, and the side effects of frequently prescribed medications.
  • Premature Ejaculation: Inability to control the ejaculatory response for at least thirty seconds following penetration is referred to as premature ejaculation. When ejaculation occurs before a man is able to fully insert his penis into his partner’s vagina this becomes a fertility issue.
  • Retrograde Ejaculation: In some conditions, the bladder sphincter does not close during ejaculation and semen gets ejaculated into the bladder rather than out through the urethra. Urine may be cloudy after ejaculation. This condition affects 1.5% of infertile men. Retrograde ejaculation can be the consequence of several conditions: Surgery to the lower part of the bladder or prostate, diseases such as diabetes and multiple sclerosis, spinal cord injury or surgery, medications such as tranquilizers, certain antipsychotics, or blood pressure medications also may cause temporary retrograde ejaculation.

Genetic Disorders

Certain inherited disorders can impair fertility.

  • Cystic fibrosis can cause missing or obstructed vas deferens.
  • Polycystic kidney disease in which large cysts to form on the kidneys and other organs during adulthood, may cause infertility as the first symptom if cysts develop in the reproductive tract.
  • Klinefelter’s Syndrome is a genetic condition in which each cell in the human body has an additional X chromosome. Klinefelter’s Syndrome eventually causes all active testicular structures to atrophy. It is impossible to improve fertility once testicular failure has occurred.
  • Kartagener syndrome, a rare disorder that is associated with a reversed position of the major organs, also causes impaired sperm motility.

Psychological/Physical/Behavioral Problems:

Several sexual problems exist that can affect male fertility. These problems are most often both psychological and physical in nature. It is difficult to separate the physiological and physical components. Stress can be an important reason for infertility. Ejaculatory Incompetence is a rare psychological condition prevents men from ejaculating during sexual intercourse even though they can ejaculate normally through masturbation. This condition sometimes responds well to behavioral therapy.


Bicycling may affect fertility and leads to impotence in men. Pressure from the bike seat may damage blood vessels and nerves that are responsible for erections. Mountain biking, exposes the perineum to more extreme shocks and vibrations and increases the risk for injuries to the scrotum. This can be reduced by using a padded or contoured bike seat set at the proper height and angle.

Environmental Factors

Sperm count may get affected by occupational or other long-term exposure to certain types of toxins such as herbicides and pesticides by either affecting testicular function or altering hormone systems. Chronic exposure to heavy metals such as lead, cadmium, or arsenic may affect sperm quality.


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M.D(O&G) FNB(Reproductive Medicine), FICOG

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