Causes of Male Infertility

Understanding the causes of infertility in men requires an explanation of the complex processes that govern male fertility, as well as specific necessary conditions. These include:

The production of healthy sperm: This necessitates the normal development and growth of the male reproductive system during puberty, regular production of male hormones responsible for stimulating sperm production—such as testosterone—and the proper function of at least one of the testicles.
Transporting sperm: After being produced in the testicles, sperm travels through delicate tubes to mix with seminal fluid before being expelled during ejaculation. Any disruption in the transport of sperm can lead to infertility.
Sufficient sperm count: A low sperm count in the ejaculate decreases the likelihood of fertilizing an egg and achieving pregnancy. A sperm count is considered low if it is below 39 million sperm per ejaculation or fewer than 15 million sperm per milliliter of semen.
Integrity of sperm: Sperm must possess normal vital functions and the ability to swim effectively to reach and fertilize an egg.

In general, male infertility can result from health issues that reduce sperm production, impair its functionality or mobility, or obstruct its exit from the body. In some rare cases, it may arise from disorders affecting the pituitary gland and hypothalamus in the brain that indirectly affect the testicles. Additionally, many cases of male infertility remain unexplained. Below are the primary causes of male infertility:

Varicoceles

It is important to note that having varicoceles does not necessarily mean a man will experience infertility. Many men with varicoceles do not face reproductive challenges. However, varicoceles can affect sperm production and its normal development by hindering proper blood drainage from the testicles, potentially increasing testicular temperature, which also negatively impacts sperm production and reduces the chances of conception.

Sexually Transmitted Infections Affecting the Testicles

One significant example is mumps orchitis, where the mumps virus can harm the testicles and salivary glands, potentially leading to long-term damage.

Undescended Testicles

Also referred to as cryptorchidism, this condition occurs when one or both testicles fail to move from the abdominal area—where they develop in utero—into the scrotal sac before birth. While many cases resolve naturally during early childhood, failure to do so without appropriate treatment can impair testicular function.

Injury to the Testicles

Trauma to the testicles can result in damage that decreases testosterone production. If only one testicle is harmed, it may not adversely affect testosterone levels.

Immune Infertility

In rare instances, a man’s infertility may stem from an autoimmune disorder in which antibodies are produced that attack and weaken the sperm.

Certain Tumors and Treatments

Cancers and tumors can impact male fertility. Additionally, treatments such as chemotherapy and radiation therapy directed at the reproductive organs or surrounding areas—like the abdomen, pelvis, spine, or even the brain, which may affect the pituitary gland—can result in diminished sperm and testosterone production. However, many individuals regain normal testicular function within several months after completing treatment.

Disorders Affecting Sperm Transport

The following outlines disorders that impact sperm transport within the male reproductive system, possibly leading to infertility: The system comprises numerous tubules responsible for sperm transport, and infertility can arise from congenital defects that hinder the growth of one or more of these tubules. Additionally, blockages can occur in any of these tubes, such as the vas deferens, epididymis, ejaculatory ducts, or urethra. Conditions like cystic fibrosis and previous surgeries or injuries may lead to such obstructions.

Ejaculation Issues

Several types of ejaculation disorders may affect men, including:

Premature ejaculation: The most common ejaculation disorder characterized by rapid ejaculation during sexual intercourse.
Delayed ejaculation: A condition where ejaculation is significantly delayed, sometimes taking 30 minutes or longer, or there is an inability to ejaculate despite having an erection.
Retrograde ejaculation: A less common disorder where ejaculation occurs backward into the bladder rather than through the urethra.

Secondary Hypogonadism

Secondary hypogonadism occurs when the pituitary gland or hypothalamic function is impaired, leading to reduced levels of hormones that stimulate the testicles to produce testosterone. The gonadotropin-releasing hormone (GnRH) produced in the hypothalamus typically triggers the pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which in turn stimulate testosterone production from the testicles. Disruptions in this hormonal chain impact testosterone production. Factors contributing to secondary hypogonadism include:

Certain genetic disorders, such as Kallmann syndrome.
Elevated prolactin levels beyond normal ranges.
Injury or surgical damage to the pituitary gland or hypothalamus, as well as infections or exposure to radiation.
Chronic use of corticosteroids or opioids.
Nutritional disorders, including rapid weight loss or gain.
Substance abuse.
Chronic illnesses involving infection or inflammation.
Hemochromatosis, characterized by elevated iron levels in the body.

Chromosomal Disorders

Certain chromosomal or genetic disorders can affect male fertility, such as Klinefelter syndrome, which results from abnormalities in the genes responsible for male characteristics. Affected individuals typically have an extra copy of the X chromosome alongside one Y chromosome, leading to impaired testicular development and reduced testosterone production.

Idiopathic Infertility

A significant percentage of male infertility cases—between 40% and 50%—are classified as idiopathic, meaning the underlying cause remains undetermined despite thorough evaluations of all potential contributing factors. Notably, there may be cases where a man’s semen analysis shows normal results, and the female partner exhibits no visible health issues, yet pregnancy still does not occur. Importantly, idiopathic infertility does not negate the availability of medical interventions to assist affected individuals in having children.

Factors Increasing Risk of Male Infertility

Several factors can elevate a man’s risk of infertility, including:

Alcohol consumption.
Smoking.
Obesity.
Drug use.
Exposure to certain toxins, industrial chemicals, or heavy metals like lead.
High stress or severe depression.
Excessive heat exposure to the testicles.
Some types of infections.
Injuries to the testicles.
A family history of fertility disorders.
Major surgical procedures in the pelvic or abdominal regions.
Chronic health conditions, such as sickle cell disease.
Issues with sexual function, including erectile dysfunction.

Treatment for Male Infertility

Treatment for male infertility primarily depends on its underlying cause. Some individuals may require surgical procedures to correct congenital defects or damage within the male reproductive system. Medication may also be necessary to address hormonal imbalances contributing to infertility. Additionally, assisted reproductive technologies and procedures to facilitate sperm transfer to the egg may be considered.

For more information on infertility treatment, please refer to the following article: (Infertility Treatment).

To learn more about infertility, you can read the following article: (What is Infertility).

Footnotes:

(1) Kallmann syndrome represents a form of hypogonadotropic hypogonadism characterized by a deficiency in gonadotropin secretion, resulting from decreased levels of specific hormones critical for sexual development. This syndrome typically manifests as delayed or absent puberty along with an inability to perceive certain smells.

Video on Causes of Male Infertility

The following video discusses the causes of male infertility.