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The effect of age on male fertility

There has been a wealth of research on the impact of age on female fertility, with it being well understood that the number of eggs and the quality of these eggs naturally decline as a woman gets older.

But what about age and male fertility?

While it’s true that men can remain fertile much later into life than women, it’s one of the male fertility myths that age doesn’t matter. In fact, male age is becoming an increasingly important factor in fertility conversations and for good reason.

The average age of fathers in the UK has been steadily rising over the past four decades and is now the highest it has been since the Office for National Statistics began collecting this data in 1964. Many countries are seeing more men becoming parents after the age of 40, whether due to later-life relationships, career focus, or simply waiting until they feel ready. In the U.S., for example, the number of men over 40 fathering children has increased by 30% since 1980. As this trend continues, it’s important to understand how male age can impact fertility and the health of future children.

You may just be thinking about having children or have been trying to conceive for a while without success. Even if you’re not quite ready to explore assisted conception or sperm donation, understanding the role age plays in male fertility can help you feel better informed and in control of your family planning journey, now and in the future.

Does sperm count decrease with age?

The short answer is yes. Sperm count and other key measures of sperm health can decline with age. While it’s hard to give an average, a normal sperm count ranges from 16 million to more than 200 million sperm per millilitre of semen. Some studies suggest that sperm concentration can decrease up to 3.3% per year of age, while other research indicates that, as well as sperm concentration, semen volume, and total sperm count also decreases with age.

However, it’s not just about quantity. While men never stop creating sperm (unless they are affected by a specific condition or damage to the testicles), there’s increasing evidence showing that sperm quality can be affected by the passage of time.

This decline can affect fertility rates and impact the success of assisted reproductive technologies (ART) such as in vitro fertilisation (IVF).

At what age is sperm count highest?

This isn’t straightforward to answer as sperm count can vary between individuals, as can the rate at which it reduces. However, sperm production begins during puberty and tends to peak in a man’s early to mid-20s. During this period, the body’s natural sperm production is at its most efficient and testosterone levels tend to be highest.

From a biological perspective, this is when men are generally most fertile. After the age of 35, studies suggest that sperm quality begins to decline gradually, with more noticeable changes becoming apparent in the 40s and 50s. When compared to males aged 21-30 years, men over the age of 50 are:

2 times more likely to have lower semen volumes

2 times more likely to have lower sperm concentration

6 times more likely to have a lower total sperm count

12 times more likely to have impaired progressive sperm motility

That said, age isn’t the only factor at play. A man in his 40s who is in excellent health may have better sperm parameters than a younger man with poor lifestyle habits. This makes male fertility a multifaceted issue, where age is one piece of a bigger picture.

The effects of age on sperm

It isn’t just the amount of sperm a man has that determines his fertility. Other aspects of sperm, such as how they are shaped and how they move, also play a significant role. Some of the most common effects of age on the sperm include:

Sperm production

From the age of 30, testosterone levels typically begin to decline at a rate of approximately 1% per year. This natural change can reduce libido, contribute to erectile dysfunction and alter muscle mass and fat distribution in the body. Additionally, lower testosterone levels can impact how sperm cells mature, affecting overall sperm production.

Decreased motility

Sperm that has not matured will not have adequate motility to reach and penetrate the egg. Research indicates that progressive sperm motility decreases with age. Also, with age comes a decreased ability to have strong ejaculations, thus decreasing the distance that the sperm will travel upon ejaculation.

Decreased strength

Immature sperm will not have the needed strength to travel the distance to the egg, nor to penetrate the membrane for fertilisation.

Increased sperm morphology defects

For sperm to successfully reach and fertilise an egg, the tail of a sperm cell must propel it through the female reproductive system, and the head of a sperm cell must help it penetrate the egg’s outer layer. However, research has found that age can impair sperm morphology and increase the likelihood of defects.

DNA fragmentation

Sperm DNA fragmentation refers to the presence of broken or damaged DNA strands within sperm cells. Studies suggest that the level of DNA fragmentation tends to increase as men age, which may affect overall sperm quality.

Other factors that can affect sperm count

While age is important, it’s not the only factor that can influence sperm health. Lifestyle, environment, and general health play a crucial role and can either offset or compound the effects of ageing.

Some key factors that can be detrimental to sperm count and quality include:

• Smoking and vaping: It can reduce sperm count and motility and increase morphology defects.
• Alcohol: It can impact sperm quality and quantity.
• Obesity: Impacts hormone levels, which can impact fertility.
• Testicular heat exposure: Prolonged use of hot tubs, saunas or tight underwear can negatively impact sperm production.
• Exercise: High-intensity or excessive exercise can be detrimental to sperm. For example, cycling can affect fertility by impacting sperm morphology and motility.
• Environmental toxins: Pesticides, heavy metals and industrial chemicals may interfere with sperm health.
• Chronic stress and poor sleep: Such lifestyle factors can disrupt hormone balance, which in turn, impacts sperm production.
• Poor nutrition: A lack of folate, zinc, vitamins C and E, selenium, omega-3, and antioxidants can impair sperm function.

Risk factors associated with increased paternal age

While conception is still possible for many men later in life, age-related changes in sperm can have implications for both fertility and offspring health. These include:

Longer time to conception

Couples may find it takes longer to get pregnant when the male partner is older, even if the female partner is in her 20s or early 30s. A 2020 study found that conception is 30% less likely for men over 40 than it is for men under 30.

Increased risk of miscarriage

Some studies have identified a correlation between spontaneous miscarriage and paternal age. The risk of miscarriage is 1.27 times higher when the father is over 35 and increases further for fathers over 45. This is thought to be linked to sperm DNA damage or genetic abnormalities.

Higher risk of certain conditions in offspring

Advanced paternal age has been associated with a small but increased risk of conditions such as autism spectrum disorders, schizophrenia, bipolar disorder and cleft palate. These risks are still low in absolute terms, but statistically higher when compared to younger fathers.

None of this is to say that men over 40 shouldn’t pursue fatherhood; many do so successfully. However, being informed about these risks can help shape realistic expectations and guide decisions about timing and fertility support.

Treatment for infertility as a result of male age

If you’re struggling to conceive and suspect age may be playing a role, you’re not alone, and you’re certainly not without options. While male fertility doesn’t decline as sharply as it does for women, age-related changes in sperm quality can make conception more difficult over time. However, help is available, and taking the first step to explore it can be empowering.

For couples or individuals trying to conceive without success, especially after a year of trying naturally (or six months if the female partner is over 35), it may be time to seek support from a fertility specialist. A semen analysis is often a good starting point. This simple test assesses sperm count, motility, and morphology, offering insight into whether male age may be contributing to fertility challenges.

Depending on the results, potential next steps could include:

• Lifestyle improvements: In many cases, making changes to diet, exercise, alcohol use, and other factors can help improve sperm health.
• Medical treatment: Some men may benefit from hormonal therapy or other interventions to support sperm production.
• Assisted reproductive techniques: Treatments such as intrauterine insemination (IUI) or in vitro fertilisation (IVF) may be recommended to improve the chances of conception.
• Using donor sperm: For those with significantly reduced sperm function, using donor sperm for fertility treatment can be a route to parenthood, either as a first-line option or after other treatments haven’t been successful.

If you reach a point where donor sperm becomes part of the conversation, it’s perfectly normal to have mixed feelings.

When you feel ready, you may want to find a donor. Many people start with London Sperm Bank by browsing our sperm donor catalogue, which offers detailed profiles of available donors. These include information about the donor’s background, physical characteristics and education.

Knowing how to choose a sperm donor can feel overwhelming at first, but we offer guidance to help you navigate the process. Once you’ve made your selection, the sperm donor ordering process is straightforward and handled with discretion and care.

Choosing to explore donor sperm doesn’t mean you’ve set your path to parenthood in stone; it simply means you’re keeping doors open. Even if you’re not quite there yet, just knowing it’s an option can bring comfort and clarity as you weigh up your choices. If you do want to find out more, you can check our find a donor FAQs or contact us.

References

Birth characteristics in England and Wales: 2022 (May 2024)

Fertility and the Aging Male – PMC (2011)

The effects of aging on semen parameters and sperm DNA fragmentation – PMC (January 2020)

Impact of age on semen parameters in male partners of infertile couples in a rural tertiary care center of central India: A cross-sectional study – PMC (August 2017)

Fertility in the aging male: a systematic review – ScienceDirect (December 2022)

The Male and Female Reproductive Journey: A Comprehensive Timeline – European Fertility Society (October 2024)

Age-Related Changes in Sperm Morphology and Analysis of Multiple Sperm Defects – PubMed (September 2023)

Low sperm count – NHS (January 2024)

Male Fertility (April 2024)

Advanced paternal age is associated with an increased risk of spontaneous miscarriage: a systematic review and meta-analysis – PMC (May 2020)

Advancing paternal age and risk of autism: new evidence from a population-based study and a meta-analysis of epidemiological studies – PubMed (December 2011)

Advanced paternal age: How old is too old? – PMC (October 2006)

Advanced paternal age and risk of schizophrenia in offspring–review of epidemiological findings and potential mechanisms (July 2022)

Advancing Paternal Age and Bipolar Disorder (September 2008)