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Age and male fertility: What men need to know

Diferencias inseminación artificial vs fecundación in vitro

Did you know that a man’s age also has an impact on the probabilities of achieving pregnancy? The fertile years of a man are longer than those of a woman, which is why many men are less concerned about delaying fatherhood. While it’s true that sperm production remains active into old age, it’s worth noting that both the quantity and quality of sperm start to decline after the age of 35.


Testosterone, the main male sex hormone, plays a key role in sexual performance. As we age, testosterone levels tend to decline, which reduces sexual desire and makes it more difficult to maintain an erection. At the same time, the levels of FSH and LH, which regulate sperm production, tend to increase as sperm-producing cells become less efficient.

As men age, genetic risks may increase. Therefore, it’s recommended to analyse sperm quality and carry out genetic studies to monitor the risk of embryo alterations. Scientific evidence has confirmed that there are changes in sperm membrane permeability in men over the age of 35. These changes affect the regulation of substances, allowing toxins to penetrate and nutrients to be eliminated, causing stress on the sperm. Stress impacts the sperm nucleus, which holds the DNA strands. As a result, the DNA fragments.

Fragmented DNA sperm may fail to fertilise the egg, or produce embryos that are typically of poorer quality and more likely to stop developing, causing miscarriage, implantation failure or genetic abnormalities in the baby. There may also be changes in the number of chromosomes in the sperm, an accumulation of mutations or epigenetic alterations.

In addition, a decrease in sperm motility is also common. Approximately 0.7% of progressively motile sperm are lost each year. This means that if a 22-year-old man has an average of 25% immotile sperm, a 30-year-old man has 40%, and this rises to 60% and 85% in men aged from 40 to 60 respectively.

It should also be noted that men over the age of 45 take about 5 times longer for pregnancy to be achieved than men under the age of 25. For this reason, it’s advisable to carry out an andrological study, a fragmentation test, and a semen analysis to assess all these parameters and determine whether there are any alterations in the sperm, so as to receive the appropriate advice.


As mentioned above, after the age of 35, sperm count decreases and DNA fragmentation increases.  This can affect pregnancy rates with techniques such as IVF, as well as increasing the risk of premature babies with low birth weight.

Therefore, we could say that the ideal age to become a father is under 35, and the older the man, the less likelihood there is of conceiving naturally, and the higher the genetic risks in embryos. However, this doesn’t mean that it’s not possible to become a father after this age.

Techniques such as ICSI can help overcome certain age-related sperm quality issues. A Preimplantation Genetic Diagnosis (PGD) can also be carried out, especially if the couple are of advanced maternal age. This ensures that embryos with genetic abnormalities are not transferred.

Assisted reproduction treatments can compensate for this reduction in fertility and reduce the risk of genetic abnormalities and miscarriages.

The Spanish Law 14/2006 on ART doesn’t set an age limit for the use of assisted reproduction techniques for men, as long as the woman is of legal age. An age limit of 50 years is recommended for women, but there is no consensus for men.

To sum up, age is a significant factor in male fertility and in their future children’s health. It’s therefore very important to be aware of this fact, and to take action so as to avoid the consequences. By taking into account how age impacts fertility, we can make informed family-planning decisions, and ensure the health of our future children.

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