Causes of Male Infertility

ben bunting BA(Hons) PgCert Sport & Exercise Nutriton  Written by Ben: BA(Hons), PGCert.


Contemporary data suggests that male infertility figures are on the rise, and it is a global trend that is having an impact amongst 15% of couples looking to conceive. [1]

Figures suggest that sperm counts across the world have halved over the past 40 years which has left 1 in 20 men suffering with the prospect of a reduction in their fertility. [2]

To compound the issue further, an article published in the Social Science & Medicine journal outlines that men’s health within the developed West is on the decline which is also a cause of concern.

The article raises the point that men seem to be less likely to come forward and disclose any medical issues due to the threat it may pose towards their masculinity. [3] With these sentiments in mind, the real figure for male infertility could be much higher than the data collated by global health organizations.

What's covered in this article:

  • What is male infertility?
  • Male vs female infertility
  • Causes of male infertility
  • Final note

What is Male Infertility?

man on his phone holding a bike

First though, let’s consider what male infertility is, because it is not just a clear-cut singular issue. It can be the result of a number of biological problems and the result of different environmental factors.

When a couple wish to conceive, if they have been unsuccessful after a period of 12 months’ worth of unprotected sex then it is considered there is a fertility issue. [4]

This is all well and good, but there’s a 50% chance the infertility could be either the male or female, or even a possibility both are infertile.

In plain English, the National Health Service of the United Kingdom points towards poor semen quality as being a common reason for male infertility, it is the semen that contains the sperm. [5]

However, the health authority also outlines a low sperm count, sperm that has poor mobility or the sperm being an abnormal shape being associated causes for male infertility, too.

A more clinical definition of male infertility is when there are two abnormal semen parameters when analysed a month apart. Or as the World Health Organization likes to put it, when there is the presence of more than one abnormality in the semen or an inadequacy of sexual or ejaculatory function. [6]

It must be noted that even with this information available, it is reported that most cases of male infertility are of an unknown origin, so many men may not know the root cause of their medical condition. [7]

Male vs Female Infertility

If you are thinking that male infertility doesn’t appear to be discussed as much or a widespread topic of discussion compared to female infertility, you are on the right track. Even so, with figures suggesting there are at least 30 million men being infertile we tend to hear little about treatments. [8]

Why is this? 

IVF Fertility Treatment

Arguably this could be due to the success of in vitro fertilization (IVF) which saw the first baby to be conceived and later born in 1978. [9] This is an invasive procedure whereby the egg is removed from the woman’s ovaries, fertilized with a sperm in a laboratory then returned to the womb. Due to its (some may suggest limited) success, it is speculated the procedure triggered further female centric fertility research. [10]

Even so, the highest rate of live births between 2014 and 2016 was 29% for women under 35 who were previously unable to conceive following 2 years of regular unprotected intercourse or 12 cycles of artificial insemination. This rate of success diminishes dramatically as the female gets older, to the point that there’s only a 2% chance of a live birth through IVF for women over 44. [11]

Plus, there are some health risks associated with IVF which can range from hot flushes and headaches to multiple births and even ovarian hyperstimulation syndrome whereby there are too many eggs developing in the ovaries. [12]

As a result, even with the risks involved, the invasiveness of the procedure for women and the consideration that male infertility is associated with overall male health, there remains a large knowledge gap or treatment for male infertility. [13]

Male Infertility Treatment Options

This is due to a number of factors; we have already mentioned that it could be a social (confidence and pride) issue for a man to step forward (more so than a woman), yet in the US there isn’t a sole national registry that collates information regarding male fertility rates, therefore who really knows what procedures and facilities need to be put in place?

While there are a few organizations that do conducts surveys amongst the US population to gather information regarding family life, pregnancy, fertility, and other aspects of health their statistics often paint an unclear picture of the true reality, and in some cases do not detail infertility related services. [14]

Fertility Treatment Insurance Coverage

Furthermore, there are regional differences in the access to infertility care facilities which vary depending on population density, mandated health insurance coverage or whether a particular state even has a male reproductive urologist at all (in 2010, thirteen states didn’t).

Additionally, those states that mandate insurance coverage for fertility stands at fifteen for females and only eight for males [15] with varying degrees of coverage provided by insurers and most patients not being covered at all as reproductive healthcare is considered a lifestyle choice. [16]

Another barrier is the high cost associated with the evaluation and treatment of male infertility in the US which is considerably higher than any other developed nation in the world [17] with costs reaching $15,000. [18]

What we can see is a clear disparity between the provision of services fuelled by different factors, which ultimately does not promote a further understanding of male infertility.

Typical Causes of Male Infertility

Male infertility can be difficult to diagnose (regional access to care, the barrier of cost and social male acceptance) and difficult to trace.

However, research has and does happen. We know that the most common problem lies with sperm growth and production, but what causes these irregularities?

Under normal circumstances the male body will produce sperm, which is initiated by the sex hormones, these are:

  • Testosterone
  • Follicle Stimulating Hormone
  • Luteinising Hormone

This process can take two to three months from the initiation of production until sperm is ready. [19]

In which case, in the most simplistic of terms, the male and female would have unprotected sexual intercourse and when the man ejaculates the sperm is delivered into the woman’s body and fertilizes the egg which was released from the ovary during ovulation. [20]

However, a few factors can upset this what seems like a simple process. Some causes can’t be controlled without medical intervention (or at all), whereas others are environmental, behavioural, or lifestyle choices.

Causes of Male Infertility

man smoking on the phone

Let’s take a look at the causes of male infertility as outlined by the American Urological Association [21]:

  • Sperm irregularities
  • Varicoceles
  • Retrograde ejaculation
  • Immunologic infertility
  • Obstruction
  • Hormonal
  • Medications

Furthermore, the Centers for Disease Control and Prevention list the following factors as increasing the risk of male infertility [22]:

  • Age
  • Obesity/overweight
  • Alcohol consumption
  • Smoking
  • Anabolic steroid use
  • Radiation exposure
  • Exposure of the testes to high temperature
  • Environmental toxins

In addition to the aforementioned, a review of the current literature (published since 2008), identifies the following as being contributory factors to male infertility [23]:

  • Recreational drugs
  • Psychological stress
  • Cycling
  • Sleep disturbances
  • Diet and nutrition
  • Activity

 As you can see, there are a lot of different causes and factors that can contribute towards male infertility. We shall cover each point so you can see how these issues may affect you or your partner, and how you can support male fertility.

Sperm Irregularities

One of the most common causes of male infertility is oligoasthenoteratospermia. This characterizes sperm which is low in number, is not very mobile and changes in structure and shape. [24]

Other issues can include sperm that is not fully developed or not developed at all, in the latter case this is known as azoospermia.

In some cases, damage to the reproductive system can be the cause of unhealthy sperm.


16% of men have swollen veins in the scrotum, but this condition is much higher for infertile men whereby 40% of affected. These veins block the drainage of blood which is depleted in oxygen that causes the testicles to get too warm which impairs sperm development. [25]

Retrograde Ejaculation

While not particularly common, it is a process whereby the ejaculatory fluid enters the bladder rather then exiting the body. In this instance the sperm could be completely healthy, and it can sometimes be identified if your urine is cloudy immediately after intercourse. [26]

Immunological infertility

Studies have demonstrated that anti-sperm antibodies reduce the motility of sperm making it less able to reach the egg, or unable to penetrate the cervical mucus, and thus unable to fertilize the egg. [27]


On occasion the tubes/ducts that sperm travels through may become blocked. This could be due to infection, surgery, swelling, scars, cysts, inflammation, or defects. If the tubes become blocked the sperm cannot leave the body. [28]

Voluntary obstruction can come in the way of a vasectomy, this is when the tubes (vas deferens) have been purposefully cut so the man can have unprotected sex and not impregnate their partner.


Male hypogonadism is a condition when the male’s body doesn’t naturally produce enough testosterone and their hormone levels are abnormally low. This can affect a man’s health in multiple ways, ranging from low muscle mass, heart disease, poor cognitive health, low mood, libido, and sperm production. The latter obviously will affect the chances of conceiving.

This abnormally low level of testosterone the result of a reduction of the gonads functioning properly which also produces sperm. Therefore, if the gonads are not functioning correctly, it can leave a man infertile. Fertiligy has been developed to help stimulate more natural testosterone production and improve libido. [29]


Some medications may harm the way sperm is produced, the way it functions and how it is delivered. One category of medication called Glucocorticoids that are used to reduce inflammation, autoimmune disease and allergies can have a negative effect. [30]

Paternal Age

When we looked at the success rate of live births after IVF treatment, we could see that there is a strong correlation between advancing age and failure rates. Once a woman is over 44 years of age, the chances of a live birth are extremely low.

Men also suffer from age-related infertility. A review of data has demonstrated that since the 1980s, fertility rates for men over 40 has decreased by 30%. [31]

Additionally, there is a higher chance of miscarriage or there’s a risk to the child’s development health if a man is over 45. [32]


There is a parallel between rising obesity in men worldwide with impaired semen.

A study published in 2015 identified hypotestosteronaemia being the prime cause in obese men which reduces fertility. However, studies have also found that obese related infertility can be reversible once they lose fat mass. [33]


A study which looked at over 1000 men within their prime age for fertility identified that habitual drinking of just 5 units of alcohol per week affected fertility and hormonal parameters. Those who drank 25 units or more per week saw greater reductions in semen quality. [34]


Smoking is proven to increase the risk of erectile dysfunction; smoking is also indirectly and directly linked to other areas of infertility. Some we have already mentioned such as varicocele and hormones combined with other aspects such as the formation of sperm cells and oxidative stress. [35]

Anabolic Steroids

Using anabolic steroids is associated with sperm abnormalities and induced hypogonadism. However, once the person stopped using anabolic steroids it has been noted that these side effects can be reversed over time, albeit recovery times are widely variable. [36]


When we think of radiation it is often associated with hazardous waste, but many people are subjected to higher levels of radiation in the form of cancer treatments.

Even very low doses of radiation around the groin areas can significantly impair the function of the testes which relates to infertility. [37]

It is also noted that those who have received radiation therapy should avoid having children for at least three years following treatment to prevent any genetic anomalies.  

High Temperatures

It is reported that prolonged exposure of an increased temperature to the scrotum area is associated with an adverse effect on sperm production. Even just a two degree increase in temperature exposure results in lower sperm numbers and reduced motility. [38]

One key point is that a study demonstrated by placing a laptop on the groin area for just 60 minutes increased scrotum temperatures up to 2.8 degrees which falls within the ‘danger’ zone for affecting sperm health. [39]

Sitting down for much of the day can also increase heat in the groin which may also contribute towards infertility. [40]

Environmental Toxins

Toxins such as pesticides are widely used to aid the growth of crops and foods such as fruits or vegetables. Yet, exposure to these pesticides is also related to lower male fertility rates with the highest concentrations found on strawberries, kale, apples, grapes, tomatoes, and green peppers.

Other toxins can be found in many household plastics which makes them soft and pliable, but it is not just food storage solution that place you at potential risk. These chemicals are also found in other everyday items such as sunscreen, perfumes, shampoo, solid soaps, toothpaste amongst other things and they are associated with reducing sperm quality. [41]

Recreational Drugs

Due to the nature of their legal status, thorough studies and clinical trials involving recreational drugs and their effect on aspects of health are limited.

However, much of the evidence that is available does suggest that recreational drugs ranging from marijuana, prescription opiates, opioid narcotics, cocaine, amphetamines and ecstasy all have a negative effect on male fertility. [42]

Psychological Stress

It is debated whether psychological stress causes infertility, or whether infertility causes psychological stress. [43] As a result some studies have attempted to establish whether there is a cause-effect, a study published in 2009 does suggest that stressful life events do play a role in sperm concentrations and motility. [44]


Often debated, the thought of exercise negatively impacting male fertility is not a concept many would like to accept, and there is plenty of discussion online about the matter.

An article published in 2010 by the Boston University Medical Campus mentioned the plausibility of cycling and low sperm concentrations to be linked. [45]

Since then and up to 2014 there have been plenty of contradicting messages online debunking the studies. However, in 2015 a study saw that sixteen weeks of low-to-intensive bicycle training does appear to have a negative effect on sperm health which was still evident after a 30-day recovery period. [46]

Sleep Duration

There is a link between short sleep (less than six hours) and long sleep duration (more than nine hours), notwithstanding late bedtime with impaired sperm health according to a study from 2017 that evaluated nearly one-thousand men. [47]

The optimum amount of daily sleep for adults is seven to nine hours per night, but no more than nine on a regular basis unless paying off a sleep-debt. [48]

Diet and Nutrition

A diet lacking vitamins, minerals and antioxidants compounded by high calorie foods, saturated fatty acids, trans fats and processed meats contribute to male infertility. [49]

Furthermore, while not often considered, a diet enriched with plant metabolites exhibit high levels of antioxidative properties which are showing promising results to help protect sperm cells. [50]

It is also worth noting that caffeine has the potential to reduce male fertility by damaging sperm DNA. Just 308mg of caffeine which equates to less than 3 cups of coffee have shown to increase double strand breaks in sperm DNA. [51]

However, these findings also contrast against other studies, therefore it is not clear cut, but if you are a heavy consumer of caffeine you may wish to reconsider if you are wanting to improve your fertility levels.

Physical Activity

A study examining physical activity and body composition between men and women in France discovered that those who lead a sedentary lifestyle are more at risk from unexplained infertility problems. [52]

A further study of Danish men found that those who spent five hours of television per day had lower sperm concentrations which was also related to decreases in testosterone compared to those men who did not watch five hours of television. It was also reported in the same study that higher rates of physical fitness had a positive association with sperm count. [53]

These findings correlate with a study published in 2017 that also demonstrated those who were more physically active had better semen fertility parameters. [54]

Final Note

man incline dumbbell bench press

As we can see, the causes of male infertility are centered around the reproductive organs and the development of sperm. The most common issue that causes infertility is sperm irregularities, but there’s other issues such as blockages, swollen veins or even the sperm not being ejaculated.

What Factors Affect Fertility?

It is worth acknowledging that there are a lot of lifestyle factors that influence sperm health, and once aware, these factors can be adjusted which can then have a positive impact.

For instance, it has been demonstrated that if a person reduces their body weight, the negative impact on sperm health is reversible, this is also apparent once a person stops using anabolic steroids.

Alcohol, caffeine consumption and smoking should be reduced or stopped altogether during the period in which a couple wished to conceive and there should be more priority focussed of achieving the optimum sleep duration. If you like cycling, planned breaks during training or rides can help alleviate the pressure and we can make a concerted effort to wear looser clothing or sitting less to regulate groin temperature.

Using a desk to work from or browse the internet rather than resting items such as phones and laptops on our groin area can help, as can doing more physical exercise, the latter, particularly resistance training can help improve testosterone levels as well as mood. [55]

As ever, a common-sense approach to diet and nutrition should be taken. Foods that are generally perceived as ‘junk’ or unhealthy should be avoided as saturated fatty acids and trans fats result in the accumulation of fat-soluble toxicants in the testicular environment which leads to unhealthy sperm and low testosterone. [56]

Therefore, it will come as no surprise to hear that evidence shows that good nutrition, including antioxidants, carotenoids and carnitine can combat reactive oxygen species and inflammation while boosting male fertility. [57] It has been noted that nutrition is one of the major environmental factors that influences the reproductive system, as such this should be your priority. [58]


fertiligy male fertility vegan friendly supplement


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