Male infertility is one of the leading causes of difficulty conceiving, often linked to issues with sperm production, quality, or transport.
Male infertility refers to a man’s inability to contribute to conception, either due to problems with sperm production, sperm function, or sperm delivery. It is a significant factor in around 40–50% of couples facing difficulties in conceiving, highlighting that fertility challenges are not solely a female concern.
Physiology of Male Reproduction
The male reproductive system is designed to produce, mature, and transport sperm, the male gamete necessary for fertilising an egg. Several key structures are involved in this process:
Testes — the testes are responsible for producing sperm and the primary male sex hormone, testosterone. Sperm production, known as spermatogenesis, occurs within the seminiferous tubules located inside the testes.
Epididymis — once produced, sperm are stored in the epididymis. Here, they undergo further maturation, gaining the ability to swim and fertilise an egg.
Vas deferens — this muscular tube carries sperm from the epididymis towards the urethra, preparing for ejaculation.
Seminal vesicles and prostate glands — these glands produce seminal fluid, which nourishes and protects sperm. During ejaculation, sperm mix with this fluid to form semen.
Spermatogenesis — How Sperm Are Made
Spermatogenesis is a tightly regulated biological process that converts immature germ cells into mature, motile sperm. This process takes approximately 64 to 72 days and occurs in the seminiferous tubules of the testes. It is orchestrated by a hormonal network that includes:
Follicle-stimulating hormone (FSH) — stimulates the Sertoli cells in the testes, which support sperm development.
Luteinising hormone (LH) — triggers the Leydig cells to produce testosterone.
Testosterone — plays a key role in promoting the final stages of sperm maturation.
Proper hormonal balance and testicular function are essential for healthy sperm production. Even slight disruptions in this system, whether due to hormonal imbalances, injury, or illness, can significantly impact fertility.
Ejaculation — Delivering Sperm Effectively
During ejaculation, sperm are propelled from the epididymis through the vas deferens. As they travel, they mix with seminal fluid from the seminal vesicles and prostate, forming semen. This fluid is expelled through the urethra during orgasm. Any structural blockages, issues with muscular contractions, or ejaculatory dysfunction can prevent sperm from being effectively delivered, thereby contributing to infertility.
The male reproductive process involves the production of sperm in the testes, maturation in the epididymis, transport through the vas deferens, and ejaculation via the urethra with fluids from the prostate and vesicular glands.
What causes male infertility?
Male infertility may result from a combination of medical, physical, environmental, and lifestyle factors. Some of these affect sperm production directly, while others interfere with the ability to deliver sperm effectively.
Medical conditions
In some cases, underlying health issues can affect sperm production or function:
Hormonal imbalances — the production of sperm depends on hormonal signals from the brain to the testes. Problems in the hypothalamus, pituitary gland, or testes can lead to reduced levels of testosterone or follicle-stimulating hormone (FSH), both of which are essential for normal sperm development.
Genetic conditions — certain genetic abnormalities, such as Klinefelter syndrome (which involves an extra X chromosome) or microdeletions in the Y chromosome, can affect testicular function and reduce or eliminate sperm production altogether.
Chronic illnesses — diseases like diabetes may cause nerve damage that affects ejaculation. Cystic fibrosis can lead to congenital blockages in the reproductive tract. Infections, particularly sexually transmitted infections like chlamydia or gonorrhoea, can cause inflammation or scarring that affects sperm transport or testicular health.
Sperm production issues
Some men have problems related to the quantity of sperm in their semen, which significantly reduces the chances of natural conception.
Azoospermia — it refers to a complete absence of sperm in semen. Azoospermia may occur due to testicular failure, hormonal dysfunction, or obstructions that block sperm from entering the ejaculate.
Oligospermia — in oligospermia, the number of sperm in the ejaculate is below the normal threshold, which reduces the likelihood of successful fertilisation even when sperm are motile and structurally normal.
Contact with environmental toxins such as heavy metals, industrial chemicals, radiation, or pesticides can negatively impact sperm count and motility. Prolonged exposure to heat, including frequent use of hot tubs or saunas, may also impair sperm development by raising testicular temperature.
Lifestyle factors
Smoking, heavy alcohol use, and drug abuse are known to reduce sperm quality and increase DNA damage. Obesity can disrupt hormonal balance, leading to lower testosterone levels and poor sperm production. A sedentary lifestyle and poor diet lacking in essential nutrients may also contribute to reduced fertility over time.
What are the signs of male infertility?
Male infertility doesn’t always present with obvious symptoms. In many cases, the only sign is the inability to conceive. However, certain physical or hormonal changes may suggest an underlying issue.
Inability to conceive after 12 months of regular unprotected intercourse
Low libido or reduced sexual desire
Difficulty achieving or maintaining an erection (erectile dysfunction)
Problems with ejaculation, including low semen volume or retrograde ejaculation
Pain, swelling, or a lump in the testicles or scrotum
Decreased facial or body hair, or other signs of low testosterone
Small, soft, or firm testicles
Development of breast tissue (gynecomastia)
Unexplained fatigue or mood changes
Can male infertility be prevented?
While not all causes of male infertility can be prevented, especially those related to genetics or congenital issues, many risk factors can be minimised through lifestyle and environmental awareness.
Avoid exposure to excessive heat — prolonged use of hot tubs, saunas, or tight-fitting underwear can raise scrotal temperature and impair sperm production.
Limit exposure to environmental toxins — reduce contact with pesticides, heavy metals, radiation, and industrial chemicals that can harm sperm quality.
Maintain a healthy weight — obesity is linked to hormonal imbalance and reduced sperm count. Achieving a healthy body weight supports better reproductive health.
Quit smoking and reduce alcohol intake — tobacco and excessive alcohol consumption can negatively impact sperm motility and increase DNA damage.
Manage chronic health conditions — keep conditions like diabetes, thyroid disorders, and hypertension under control with regular medical care.
Protect against sexually transmitted infections (STIs) — practise safe sex to prevent infections such as chlamydia and gonorrhoea, which can damage reproductive organs.
Avoid anabolic steroids and recreational drugs — steroid use and certain drugs can suppress sperm production and lead to long-term fertility issues.
Minimise stress and prioritise sleep — high stress levels and poor sleep can interfere with hormonal balance and overall sperm health.
How is male infertility diagnosed?
Diagnosing male infertility begins with understanding the man's medical background, followed by physical examination and a series of targeted investigations. These tests help identify whether the issue lies in sperm production, hormone regulation, or structural abnormalities in the reproductive tract.
Medical history and physical examination — the doctor will ask about previous illnesses, surgeries, medications, lifestyle habits, and any history of infertility or genetic disorders in the family. A physical examination checks for testicular abnormalities, signs of varicocele (enlarged veins in the scrotum), or any visible signs of hormonal imbalance such as reduced body hair or breast enlargement.
Semen analysis — this is the primary test for assessing male fertility. A semen sample is collected and analysed in a laboratory to measure sperm concentration (count), motility (movement), and morphology (shape). A low sperm count, poor movement, or abnormal shapes may indicate problems with sperm production or maturation.
Hormone testing — a blood test is used to measure levels of key reproductive hormones such as follicle-stimulating hormone (FSH), luteinising hormone (LH), testosterone, and prolactin. Abnormal levels may suggest problems with the hypothalamus, pituitary gland, or testes that interfere with spermatogenesis.
Scrotal ultrasound — an ultrasound scan of the scrotum can help identify physical abnormalities such as varicoceles, cysts, or tumours that may be affecting testicular function or sperm transport.
Transrectal ultrasound (TRUS) — this scan involves inserting a small probe into the rectum to examine the prostate, seminal vesicles, and ejaculatory ducts. It is particularly useful in detecting obstructions that prevent sperm from being ejaculated.
Genetic testing — in men with very low sperm counts or azoospermia, genetic tests may be recommended to detect chromosomal abnormalities (e.g. Klinefelter syndrome) or Y chromosome microdeletions that disrupt sperm production.
Post-ejaculation urinalysis — if semen volume is low or absent, a urine sample collected after ejaculation may be tested for the presence of sperm. This helps diagnose retrograde ejaculation, a condition where semen flows backward into the bladder instead of out through the urethra.
Testicular biopsy — in select cases, a small tissue sample is taken from the testicle and examined under a microscope. This helps determine whether sperm are being produced at all, especially when semen analysis shows azoospermia.
Infectious disease screening — in some cases, blood tests are used to screen for sexually transmitted infections (STIs) such as chlamydia and gonorrhoea, as well as viruses like HIV, hepatitis B, and hepatitis C. These infections can damage reproductive organs or interfere with sperm production.
How is male infertility treated in Singapore?
Treatment for male infertility depends on the underlying cause, and may involve medical therapy, surgical correction, assisted reproductive techniques, nutritional supplementation, or lifestyle changes. In many cases, a combination of strategies is used to improve fertility potential.
Medical treatments
These treatments target hormonal imbalances, infections, or anatomical issues that may be interfering with sperm production or delivery.
Hormonal therapy — men with low levels of testosterone or other hormonal imbalances may benefit from hormonal treatments. These aim to stimulate the testes to produce sperm by correcting disruptions in the hypothalamic-pituitary-gonadal axis.
Hormone modulators — medications such as clomiphene citrate (a selective oestrogen receptor modulator) may be prescribed to boost levels of luteinising hormone (LH) and follicle-stimulating hormone (FSH), which in turn can enhance sperm production.
Antibiotics — when infections such as prostatitis or sexually transmitted infections are identified, targeted antibiotic therapy can reduce inflammation and restore sperm quality and function.
Surgery — surgical intervention may be necessary for conditions like varicocele, where enlarged veins affect testicular temperature and sperm quality. Procedures can also remove blockages in the vas deferens or repair previous surgical damage to restore sperm flow.
Assisted reproductive technologies (ART)
ART may be recommended when sperm quality is poor, sperm are absent from the ejaculate, or other treatments have not succeeded.
Intrauterine insemination (IUI) — in IUI, specially prepared sperm are inserted into the woman’s uterus around the time of ovulation. This method is useful when sperm count or motility is mildly reduced or when ejaculation issues are present.
In vitro fertilisation (IVF) — IVF involves retrieving eggs from the female partner, fertilising them in a laboratory with sperm, and transferring the resulting embryo into the uterus. In cases of severe male infertility, intracytoplasmic sperm injection (ICSI) may be used, where a single sperm is injected directly into an egg.
Supplements for improving fertility
Certain vitamins, minerals, and antioxidants may help improve sperm quality, motility, and overall reproductive potential.
Antioxidants — vitamins C and E are commonly recommended for their antioxidant properties, which help protect sperm from cellular damage and may improve count and motility. Coenzyme Q10 has also shown potential benefits in enhancing sperm movement.
Zinc and selenium — these trace elements play a critical role in sperm formation, hormone regulation, and overall semen quality. Supplementation may be helpful in men with low levels or poor dietary intake.
Omega-3 fatty acids — found in fatty fish and supplements, omega-3s are associated with improved sperm morphology and motility. They also support hormonal balance and reduce inflammation.
L-carnitine — L-carnitine is a naturally occurring amino acid that contributes to energy metabolism in sperm, helping them swim more effectively.
Lifestyle modifications
Adopting healthier habits can help restore hormonal balance, improve sperm function, and support long-term fertility.
Healthy diet — a diet rich in fruits, vegetables, whole grains, lean protein, and healthy fats provides the nutrients needed for sperm development. Avoiding excess sugar, processed foods, and saturated fats can also help reduce inflammation and hormonal disruption.
Regular exercise — engaging in moderate aerobic activity for at least 150 minutes per week can improve insulin sensitivity, support healthy testosterone levels, and reduce oxidative stress — all of which benefit fertility.
Weight management — obesity is linked to lower testosterone levels, poor sperm quality, and sexual dysfunction. Losing excess weight through diet and exercise may improve natural fertility.
Avoid toxins — men trying to conceive should avoid smoking, limit alcohol, and minimise exposure to environmental toxins such as pesticides, heavy metals, and plastic-based chemicals (e.g. BPA) that can disrupt hormone function.
Manage stress — chronic stress may interfere with hormonal signals that regulate sperm production. Mindfulness techniques, yoga, meditation, and adequate rest can help restore balance.
Stay hydrated — drinking enough water each day supports blood circulation, hormone transport, and testicular function, all of which are vital for healthy sperm production.
Summary
Male infertility is a common but often overlooked contributor to a couple’s difficulty in conceiving, accounting for up to half of all infertility cases. It may arise from medical conditions, genetic abnormalities, hormonal imbalances, lifestyle habits, or environmental exposures. Diagnosis involves a thorough assessment, including semen analysis, hormonal testing, and imaging, to pinpoint the exact cause.
Treatment is tailored to the underlying issue and may involve medications, surgery, assisted reproductive techniques like IUI or IVF, and evidence-based supplements. Lifestyle modifications also play a crucial role in supporting fertility and improving treatment outcomes. Prognosis depends on the cause and severity, but many men respond well to appropriate interventions.
Male infertility contributes to around 40–50% of infertility cases in couples. Globally, it affects about 1 in 20 men, though many remain undiagnosed until trying to conceive.
What effect does age have on male fertility?
Male fertility gradually declines with age, especially after 40. Older men may have lower sperm motility, reduced sperm volume, and increased DNA fragmentation.
Can stress or a busy lifestyle reduce sperm quality?
Yes, chronic stress and poor sleep can disrupt hormones like testosterone and impair sperm production. Managing stress and getting adequate rest may improve fertility.
Do antisperm antibodies (immune factors) cause infertility?
Yes, antisperm antibodies can develop after infection, injury, or surgery and may interfere with sperm motility or block sperm from fertilising the egg.
Can obesity affect male fertility?
Obesity can lower testosterone levels and increase oestrogen, negatively affecting sperm production and quality. Weight loss often helps restore hormonal balance.
Can testicular injuries affect fertility?
Yes, direct trauma to the testicles can damage the tissues responsible for sperm production and hormone regulation, potentially leading to reduced fertility.
Can mumps impact male fertility?
Mumps infection, especially after puberty, can cause orchitis (inflammation of the testicles), which may lead to testicular atrophy and impaired sperm production in some cases.
Will reversing a vasectomy restore fertility?
Vasectomy reversal can restore the flow of sperm, but success depends on factors like time since the vasectomy and the presence of antisperm antibodies.
How many semen tests are needed to confirm fertility status?
At least two semen analyses are typically done, spaced a few weeks apart, due to natural fluctuations in sperm parameters.
Do at‑home sperm tests provide reliable results?
At‑home sperm tests can give a basic idea of sperm count or motility but lack the detail of a full semen analysis done in a laboratory setting.
Should sperm banking be considered before medical treatment or surgery?
Yes, sperm freezing is recommended before cancer treatment, hormone therapy, or surgery that may impair fertility, which helps with future attempts at conception.
