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Men Have Biological Clocks Too: Age and Male Fertility

male fertility, age and biological clocks

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When we think of the effects of age on fertility, our minds often gravitate towards women, focusing on the declining egg supply, chromosomal issues, and infertility. One study even found that 1 in 5 men consider infertility to be only a woman’s issue. But here’s something that’s not talked about as often – the impact of age on male fertility. Are men ever advised to pay more attention to their biological clocks?

The Age Factor: Delaying Fatherhood

Surprisingly, in many countries, there’s no discouragement for older men wanting to become fathers, unlike the way older women are often advised against motherhood. The National Institute for Clinical Excellence in England and Wales, for example, recommends against the NHS offering IVF to women over 42, but there’s no such mention of paternal age in the guidance. The question of what’s considered “old” in the context of fatherhood remains largely unaddressed.

Nevertheless, research indicates that around the age of 40, men’s sperm starts to slow down, making conception more challenging. Moreover, children born to older fathers face an increased risk of conditions such as autism, schizophrenia, and leukemia.

In the United States, the trend of men becoming fathers at older ages is on the rise. In 1980, around 43 in 1,000 babies were born to men aged between 35-49. By 2015, this number had increased to about 69 in 1,000 babies.

Why Sperm Quality Matters: The Impact of Age

The age of the father also affects the quality of sperm. A systematic review in 2015, which examined 90 studies involving 93,839 subjects, revealed that a man’s age negatively impacts sperm quality, including appearance, motility, and DNA damage.

Sperm quality plays a vital role in conceiving a child. In a study involving 2,112 UK couples, it was found that men over 45 were nearly five times more likely to take more than a year to conceive compared to men under 25, even when the female partner was young.

The Risks of Having Kids Later

In vitro fertilization (IVF) outcomes for older men also appear to be less favorable. A recent study examining 11 research papers and 10,527 egg donation cycles found that increasing male age was associated with a slight decrease in the live birth rate.

Children conceived by older men are also at a higher risk of miscarriage, stillbirth, and being born preterm. This highlights the misconception that if sperm can swim and penetrate an egg, everything is fine – a notion that many, including some medical professionals, are yet to fully grasp.

Older fathers are more likely to have children with birth defects, certain cancers, and neurological disorders. Research shows that older fathers are more likely to have children with birth defects such as cleft lip, and they face an increased risk of certain childhood cancers.

So, what’s behind these alarming statistics? Why is it that we see more older fathers in the news, like male celebrities having kids into their 70s and 80s? The reason lies in the continuous production of sperm throughout a man’s life. Sperm is generated fresh every 74 days or so, and men don’t run out of it. However, research suggests that the longer the sperm production process continues, the higher the likelihood of introducing genetic mutations.

Understanding the Reproductive Process

Sperm production is based on spermatogonial stem cells, which continuously replenish themselves through cell division. However, with each replication, there’s a chance of copying errors. The older a man is, the more times these stem cells replicate, leading to more opportunities for mistakes. Children of older fathers are likely to have more genetic mutations than those born to younger ones.

While most of these mutations are harmless, some can have serious consequences. They can contribute to genetic diseases, affecting about one in every 300 live births. These “de novo” mutations are responsible for various disorders, including achondroplasia and Apert syndrome.

Moreover, the age-related changes in epigenetic marks found on DNA in human sperm can play a role. These epigenetic marks control gene expression and can be modified due to various environmental factors. These changes are not just related to sperm development but are also associated with neurodevelopment, although the exact reasons remain unclear.

Paternal Age and the Need for Awareness

It’s evident that paternal age matters, and more men are embracing fatherhood at older ages. A combination of factors, including delayed marriages, second marriages, assisted reproduction, and changing societal norms, has led to more men becoming older fathers. But as we’ve seen, it’s not without consequences.

In this landscape, companies like ExSeed have introduced innovative solutions to help men assess and monitor their fertility conveniently from home. The ExSeed at-home sperm test, paired with a smartphone app, provides men with the ability to gauge their sperm’s motility, concentration, and overall quality, all within the comfort of their own space. This empowers men to take control of their reproductive health.

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Wearing tight pants and underwear

Studies show that men who wear looser underwear have higher sperm concentration and total sperm count compared to men who wear tighter underwear. So, lose the tight clothes and wear something loose to give your testicles some air.

CONCLUSION: learn more about how heat can affect sperm quality here.


Besides higher mortality rate and various diseases, stress is associated with low sperm quality. Stress is known to be associated with lower testosterone levels and oxidative stress with both playing an essential role in producing and maintaining healthy sperm cells.

CONCLUSION: If you feel stressed, we recommend you get some help so you can have a balanced mental health. For a stress management guide, download the ExSeed app for free and start your personalized action plan today.

Physical activity

Scientific studies show that men who are physically active have better semen parameters than men who are inactive. Fertility specialists also state that regular physical activity has beneficial impact on sperm fertility parameters and such a lifestyle can enhance the fertility status of men.

Prioritizing exercise can help improve your overall health and result in healthy, fast swimming sperm cells that have good chances of fertilizing an egg.

CONCLUSION: Try incorporating exercise in your weekly schedule to you ensure exercising at least twice weekly. We recommend a combination of cardio training and strength exercise. Read more about exercise and male fertility on our blog.


Fast Food
Processed foods damage the health of sperm-producing cells and cause oxidative stress, which lead to poorer sperm quality. Heavy consumption of junk food (every week) can increase the likelihood of infertility since men who consume vast amounts of unhealthy food are at risk of having poor sperm quality. Besides harming your fertility, junk food enlarges your waistline, harms your cardiovascular system, kidneys, and more.

Eating more fruit and vegetables can increase your sperm concentration and motility. It’s important that you consume a healthy diet filled with antioxidants and that you eat vegetables every day. Foods such as apricots and red bell peppers are high in vitamin A, which improves male fertility by nurturing healthier sperm. Men who are deficient in this vitamin tend to have slow and sluggish sperm.

Sugary snacks/beverages: several times a week Excessive consumption of high sugar items can lead to oxidative stress, which negatively impacts testosterone levels and sperm motility. Sugary snacks and beverages are also highly associated with obesity and low fertility.
CONCLUSION: To boost sperm quality, stay away from fast food, processed food, and sugary snacks or beverages. You need to implement a healthy prudent diet filled with necessary superfoods needed for good sperm production. Check out our guide to Male Fertility Superfoods. For personalized guidance and support on how you can start improving your sperm health, check out the Bootcamp.


Direct heat can inhibit optimal sperm production and cause Sperm DNA damage. Sperm cells like environments that are a couple of degrees lower than body temperature. Avoid overheating from warm blankets, seat warmers, heat from your laptop, hot showers, and saunas.

Cigarette smoking

The exposure to tobacco smoke has significant negative effects on semen quality. The damage of cigarettes and nicotine of course depends on how many cigarettes you smoke per day and for how long, but even low usage (up to 10 cigarettes / day) can inhibit healthy sperm production.  

CONCLUSION: Stay as far away from cigarette smoking as possible if you care about your general health and your fertility. Read more here.

Cell phone

When you have your cell phone in your front pocket, your testicles are exposed to electromagnetic radiation, which studies have shown to damage the sperm cells. Put your phone in the back pocket of your pants or in your jacket pocket.


There is a clear association between obesity and reduced sperm quality. At least part of the reason for this is that obese men may have abnormal reproductive hormonal profiles, which can impair sperm production and lead to infertility. 

A BMI higher than 30 can lead to several processes in the body (overheating, increase in oxidative stress in the testes, sperm DNA damage, erectile dysfunction) that can have a negative impact on male fertility. This can result in problems when trying to conceive.  

CONCLUSION: BMI is one of the risk factors that influence semen quality and, for example, sperm motility.  


A beer or glass of wine now and then do not really harm sperm quality. But excess alcohol drinking (more than 20 units per week) can reduce the production of normally formed sperm needed for a successful pregnancy.

CONCLUSION: If you want to stay safe, stay under 14 units of alcohol per week. For more information on how alcohol can affect male fertility, take a look at our blog: “Alcohol and Sperm Quality”.


Studies show that women younger than 35 and men younger than 40 have a better chance of getting pregnant. Men can produce sperm cells almost through their entire life, but the sperm cell DNA is more fragile and prone to damage after the age of 40.

As men age, their testes tend to get smaller and softer resulting in a decline in sperm quality and production. These changes are partly because of an age-related decrease in testosterone level, which plays a very important role in sperm

production. Higher male age (>40 years) is not only associated with a decline in sperm production but also with increased sperm DNA fragmentation and worsened morphology (shape) and motility (movement). These negative effects make the sperm cells less qualified for egg fertilization.

CONCLUSION: with an age under 40, you shouldn’t have to worry much about age as a factor in itself. However, studies have shown a slow decline after the age of 30-35 years

and if you are above 40 years of age, your sperm quality can be affected due to increased sperm DNA damage resulting in a decrease of sperm motility and concentration. Remember that you cannot evaluate the quality of a sperm sample by just looking at it – this requires a sperm analysis.