Infertility is the inability to conceive after one year of unprotected intercourse. Male infertility refers specifically to infertility caused by male factors, and it contributes to around 50% of all infertility cases.
It is estimated that 15% of couples are infertile, with male factor infertility playing a role in up to 50% of these cases. The main causes of male infertility include low sperm production, abnormal sperm function or blockages that prevent the delivery of sperm.
Common Causes of Infertility in Men
Male infertility can be caused by a wide range of medical conditions, lifestyle factors, environmental toxins, genetic defects and sexual health issues. The most common causes include varicocele, infections, ejaculation issues, hormonal imbalances, undescended testicles, and problems with sperm production. Other potential factors are sexually transmitted diseases, injuries, chronic health problems, and lifestyle habits like smoking, alcohol use, and anabolic steroid use.
This article will provide an overview of the most prevalent causes of male infertility, outlining the diseases, diagnosis and treatment options for each one. Understanding the root causes can help guide effective treatment plans and improve a couple’s chances of conceiving.
Genetic Causes
Genetics play an important role in male fertility. Abnormalities in a man’s chromosomes or genes can cause infertility issues. Two of the main genetic causes are:
Chromosomal Abnormalities
Chromosomal abnormalities like Klinefelter syndrome, which occurs when a man has an extra X chromosome (XXY instead of XY), can lead to low testosterone levels and decreased sperm production. Klinefelter syndrome affects about 1 in 500 to 1 in 1,000 newborn males.
Men with Klinefelter syndrome tend to have small testes that produce little to no sperm. While some men may still produce sperm, the quality and quantity is often too low for conception without assistance. Treatments like testosterone therapy, fertility medications, or surgically removing testicular tissue can possibly help increase sperm production.
Y Chromosome Microdeletions
The Y chromosome contains genes important for sperm production. Microdeletions or missing pieces in specific areas of the Y chromosome can cause infertility. This affects about 1 in 2,000 to 1 in 4,000 newborn boys.
Testing can check for Y chromosome microdeletions. If present, fertility treatments like IVF with intracytoplasmic sperm injection (ICSI) may help overcome the sperm issues. Genetic counseling is also recommended.
Varicocele
A varicocele is an enlargement of the veins within the scrotum. It’s similar to varicose veins some people get in their legs, except it occurs in the scrotum.
Varicoceles are a common cause of low sperm production and decreased sperm quality, which can cause infertility. About 15% of all men and 40% of infertile men have a varicocele.
The enlarged veins prevent blood from flowing properly through the testicles, causing the temperature inside to rise. This higher temperature can damage sperm and affect their ability to function normally.
Varicoceles usually develop slowly over time. Most often they start during puberty, though they can also develop in adulthood. Men often don’t notice any symptoms with a small varicocele. Larger varicoceles may cause a dragging, aching pain in the scrotum.
Varicoceles are diagnosed through a physical exam. The doctor will examine the scrotum while the patient stands, which allows the varicocele to be more easily felt. An ultrasound of the scrotum may be done to confirm the diagnosis and rule out other possible causes.
The main treatment options for varicoceles are:
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Surgery – This involves tying off the affected vein to redirect blood flow and reduce pressure in the veins. It’s done under general anesthesia as outpatient surgery.
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Embolization – A small catheter is inserted into the vein and tiny coils or balloons are used to block the vein. This causes the varicocele to shrink. It’s done under local anesthesia.
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Medication – Hormone therapy may help improve sperm count in some cases. But surgery is usually more effective.
The success rates for treating infertility caused by varicocele is around 40-60% after surgery. The sooner treatment is done after diagnosis, the better the chances of improving fertility.
Infection
Infections in the reproductive tract can impair sperm production and cause male infertility. The most common infections that impact fertility include sexually transmitted infections (STIs) and inflammation of the prostate gland (prostatitis).
Sexually Transmitted Infections
STIs like chlamydia, gonorrhea, and trichomoniasis often have no symptoms but can cause scarring in the reproductive tract, blocking sperm passage. Untreated STIs can also lead to epididymitis, an inflammation of the coiled tube at the back of the testicle, which can damage sperm. Getting tested and treated quickly for STIs is important to avoid these complications.
Chlamydia and gonorrhea are bacterial infections treated with antibiotics. Trichomoniasis is caused by a parasite and treated with prescription anti-parasitic medication. After treatment, doctors recommend retesting in 3-4 months to confirm the infection has cleared. Using condoms consistently can help prevent contracting STIs.
Prostatitis
Prostatitis refers to inflammation of the prostate gland that can be caused by a bacterial infection. It may lead to painful urination, pain in the genital area, and fever. Bacterial prostatitis is diagnosed through medical history, physical exam, urine tests, and sometimes imaging. It’s treated with antibiotics.
Prostatitis can impair sperm motility and cause debris and pus cells in semen. It may take 3-6 months after treatment for inflammation to resolve and sperm function to improve.
Testing and Treatment
Doctors can check for STIs and prostatitis through a urine test, urethral swab, or semen analysis. They may examine sperm under a microscope to look for signs of infection.
Treating infections quickly can help minimize long-term damage. After treatment, doctors recommend waiting a few months for sperm to regenerate before retesting fertility. Improving general health through diet, exercise, and stress reduction can also aid recovery.
Ejaculation issues
Ejaculation problems can be a cause of male infertility. The two main ejaculation issues that cause infertility are:
Erectile dysfunction
Erectile dysfunction (ED) is the inability to get or maintain an erection firm enough for sex. This can prevent sperm from entering the vagina and reaching the egg. Physical and psychological causes for ED include diabetes, heart disease, obesity, stress, anxiety, relationship issues, certain medications, tobacco use, and alcoholism. Treatments include oral medications like Viagra, injection therapy, penile implants, counseling, and lifestyle changes.
Retrograde ejaculation
This occurs when semen enters the bladder instead of emerging through the penis during orgasm. Causes include prostate or urethral surgery, diabetes, multiple sclerosis, and certain medications. Symptoms include orgasm without ejaculation, cloudy urine after sex, and infertility. Treatment options include medications to contract the bladder neck, collecting sperm from urine for artificial insemination, and surgical correction of anatomical problems.
Hormonal Imbalances
Hormonal imbalances can be a common cause of male infertility. The main hormones that can impact fertility include:
Low Testosterone
Testosterone is the primary male sex hormone and is crucial for sperm production. Low testosterone, also known as hypogonadism, can result from problems in the testes themselves, or the pituitary gland in the brain which controls testosterone production. Symptoms of low testosterone include low libido, erectile dysfunction, depression, fatigue, and muscle loss. Doctors can test for low testosterone with a simple blood test, and treatment usually involves testosterone replacement therapy, either through injections, gels, or patches.
High Prolactin
Prolactin is a hormone produced by the pituitary gland that can impair production of reproductive hormones. High prolactin levels (hyperprolactinemia) can be caused by pituitary tumors, some medications, or other diseases affecting hormone regulation. Symptoms may include reduced libido, erectile dysfunction, and difficulty producing sperm. Doctors can test prolactin levels via blood tests, and treatment focuses on addressing the underlying cause, which may involve medications or surgery for a pituitary tumor.
Other Hormonal Disorders
Other hormonal issues like high estrogen levels, growth hormone deficiency, and thyroid disorders can also negatively impact fertility. Doctors may check various hormone levels via blood tests if low testosterone or high prolactin are not found. Treatment depends on the specific hormonal imbalance, and may involve medications, supplements, or lifestyle changes to restore optimal hormone levels.
Undescended Testicles
Undescended testicles, also known as cryptorchidism, is a condition where one or both testicles fail to descend from the abdomen into the scrotum during fetal development. This is one of the most common birth defects in boys and can significantly impact fertility later in life.
The testicles form inside the abdomen during early fetal development. Between 2-6 months of gestation, they normally descend into the scrotum. When this process is disrupted, the testicles may get stuck along the descent path in the abdomen, inguinal canal, or outer scrotum.
Failure of testicle descent can impair spermatogenesis and testosterone production. The higher abdominal temperature can damage germ cells, resulting in reduced sperm count and motility. Hormone levels can also be lower. Together, these effects often lead to infertility in men with undescended testicles, especially if both testicles are affected.
Surgical correction is usually performed in infancy or early childhood to move the undescended testicle into the scrotum. The earlier this is done, the lower the risk of long-term fertility issues. The surgery is called orchiopexy and involves manually guiding the testicle into the scrotum and stitching it in place. If treatment is delayed until puberty, there is a higher likelihood of permanent damage. However, even with timely correction, there is still a chance of reduced fertility later in life.
Cancer and Chemotherapy
Testicular cancer and treatments like chemotherapy and radiation therapy can impact fertility in men. Testicular cancer is most common in men ages 20-39, which overlaps with the years when many men are looking to start families.
Testicular Cancer
Testicular cancer requires treatment like surgery to remove the testicle (orchiectomy), radiation, and chemotherapy drugs. This can affect sperm production and lead to lower sperm counts or abnormal sperm after treatment. The remaining testicle may be able to compensate, but about 50% of men have reduced fertility after testicular cancer treatment.
Other Cancers
Other cancers like leukemia, Hodgkin’s lymphoma, and brain tumors are most common in childhood and adolescence. The radiation and chemotherapy used to treat these cancers can damage parts of the reproductive system like the pituitary gland or testicles. This affects hormones and sperm production later in life.
Effect of Radiation and Chemotherapy
Both radiation aimed at the pelvic area and chemotherapy drugs designed to kill cancer cells can damage sperm production. Sometimes this causes temporary infertility during active treatment, but in many cases the effects on fertility persist long-term. The higher the doses and closer the radiation is targeted to the testicles, the more likely it is to impact fertility permanently.
Environmental Toxins
Environmental toxins such as pesticides, heavy metals, and industrial chemicals can negatively impact male fertility. Studies have shown that exposure to certain toxins can reduce sperm count and motility and increase abnormal sperm.
Pesticides
Pesticide exposure has been linked to reduced semen quality and fertility issues in men. Pesticides may interfere with the male reproductive system in several ways:
- Disrupting the endocrine system and hormone levels
- Damaging sperm DNA, resulting in increased abnormalities
- Reducing sperm count and motility
Organophosphate insecticides are particularly concerning, as research shows they can impair semen quality even at low exposure levels.
Heavy Metals
Heavy metal exposure, especially to lead, cadmium, and mercury, has been associated with fertility problems in men. These metals can accumulate in the testes and epididymis, causing oxidative stress that damages sperm.
Heavy metals may:
- Reduce sperm count and concentration
- Decrease sperm motility and viability
- Increase malformed sperm percentage
- Alter male reproductive hormone levels
Overall, minimizing exposure to environmental and occupational toxins through proper handling and disposal can help protect male fertility.
Lifestyle factors
Lifestyle choices can negatively impact male fertility in various ways. Here are some of the main lifestyle factors that can contribute to male infertility:
Smoking, alcohol, and drugs
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Smoking cigarettes has been linked to reduced sperm count and sperm motility. The toxins in cigarette smoke can damage sperm and reduce fertility.
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Heavy alcohol consumption can also lower testosterone levels and sperm production. It’s recommended that men trying to conceive limit alcohol intake.
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Using certain recreational drugs like marijuana, cocaine, anabolic steroids, and opioids can temporarily reduce fertility by impacting hormone levels and sperm health.
Obesity
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Being overweight or obese can affect fertility by causing hormonal imbalances that disrupt sperm production. Obese men tend to have lower testosterone levels.
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Excess fat tissue increases the conversion of testosterone into estrogen, throwing off the hormonal balance needed for sperm production.
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Obesity can also lead to erection problems and reduced libido, which impacts the ability to conceive. Losing excess weight can improve sperm health.
Heat exposure
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Exposure to high heat, either from hot tubs, saunas, or heated laptops, can elevate testicular temperature and impair sperm production.
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The testes require a lower temperature than the rest of the body to properly produce healthy sperm.
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Avoiding hot baths and minimizing time spent with a heated laptop on the lap can help optimize sperm development.