Male Infertility: Common Causes
Infertility is still widely thought of as primarily a female issue. When a couple struggles to conceive, the instinct is often to investigate the woman first. The data tells a different story. In over a third of infertility cases, the problem lies with the man, most often due to issues with how sperm is produced or how it is delivered. Male infertility is common, it is frequently treatable, and it is consistently underdiagnosed because men are less likely to seek evaluation until the issue has persisted for some time.
Understanding what actually causes male infertility matters because it changes where the investigation begins and what can realistically be done about it.
How male fertility works?
Fertility in men depends on several things happening correctly at the same time. The testicles need to produce enough sperm. That sperm needs to be shaped correctly and able to move effectively. The sperm needs to be transported through the reproductive tract without obstruction. And the hormones that regulate all of this need to be functioning within normal ranges.
A problem at any one of these points can affect a man's ability to father a child. A semen analysis, which assesses sperm count, motility, and morphology, is the starting point for evaluating male fertility and gives the clinician a picture of which part of the system is not functioning as it should.
- Varicocele
A varicocele is an enlargement of the veins within the scrotum, similar in nature to varicose veins in the legs. It is one of the most common and also one of the most treatable causes of male infertility. Varicocele is the most frequently identified correctable cause of male infertility. The enlarged veins raise the temperature within the scrotum, and sperm production is highly sensitive to temperature.
- Hormonal imbalances
The hormonal axis that controls sperm production involves the brain, the pituitary gland, and the testicles working in coordination. When this axis is disrupted, sperm production suffers. Low testosterone is one manifestation, but it is important to note that testosterone supplementation, including through anabolic steroids used for body building, actually suppresses the hormonal signals that drive sperm production and can cause severe reductions in sperm count.
Obesity has been linked to altered hormonal profiles, with increased oestrogen levels and decreased testosterone contributing to lower sperm quality and count.
- Genetic factors
Some causes of male infertility are rooted in the chromosomes. Klinefelter syndrome, where a man carries an extra X chromosome, is one of the more common genetic causes of severely impaired sperm production. Deletions on the Y chromosome, specifically in regions that carry genes responsible for spermatogenesis, are another established genetic cause of low sperm count.
- Structural and obstructive causes
Obstruction anywhere along the pathway that sperm travel from the testicle to ejaculation results in very low or absent sperm in the semen even when sperm production in the testicle is normal. Previous infections, particularly those caused by sexually transmitted bacteria, can scar the epididymis or vas deferens and create such obstructions. Previous surgery in the groin or scrotal area can also cause damage to these structures.
- Lifestyle factors
Smoking introduces oxidative stress and DNA damage in sperm, reducing fertility potential. Consuming alcohol in excess lowers testosterone levels and damages sperm DNA. Environmental toxins such as pesticides and heavy metals interfere with hormonal function and lower sperm motility and viability.
Heat exposure regularly affects sperm production. This can be from hot baths, saunas, or occupational exposure. The testicles work best at a temp slightly cooler than the core body heat. Obesity compounds this through both direct thermal effects and the hormonal changes discussed earlier.
How male infertility is evaluated?
Semen analysis is the foundational test, measuring sperm count, the percentage of sperm that are moving, and the proportion that are normally shaped. Semen analysis together with hormone biomarkers should be the basic screening test in the evaluation of male infertility, with additional tests such as anti-sperm antibody testing and DNA fragmentation analysis performed at later stages where indicated.
Blood tests assess the hormonal axis, including FSH, LH, testosterone, and prolactin. Scrotal ultrasound can identify a varicocele or other structural abnormalities. Genetic testing is recommended when semen analysis shows very low or absent sperm count, to identify chromosomal or Y chromosome causes before treatment decisions are made.
Male fertility treatment options
The right approach depends entirely on what is causing the problem. Varicocele repair, hormonal correction, and surgical reconstruction of obstructed ducts are all options for specific causes. For cases where sperm quality is impaired but not absent, assisted reproduction techniques including intrauterine insemination and in-vitro fertilisation with or without intracytoplasmic sperm injection are available.
For men with very severe impairment or obstruction, surgical sperm retrieval combined with intracytoplasmic sperm injection offers a route to biological fatherhood that was not available a generation ago.
Addressing modifiable lifestyle factors including smoking, alcohol, weight, and heat exposure is recommended alongside any medical or surgical approach, as it improves the overall quality of sperm and the chance of a successful outcome.
Takeaways
Male infertility causes include varicocele, hormonal imbalances, genetic factors, structural obstruction, previous infections, and lifestyle contributors including smoking, alcohol, obesity, and heat exposure. Low sperm count and impaired sperm quality are the most common findings on semen analysis, which is the starting point for any male fertility evaluation.
Male fertility treatment depends on the identified cause and ranges from lifestyle modification and hormonal correction to surgical intervention and assisted reproduction. Any couple that has been trying to conceive for twelve months without success, or six months when the woman is over 35, should seek fertility evaluation that includes a thorough assessment of the male partner.