Why Sperm Matters

Eloise Edington  |   19 Nov 2021

When foetal development issues or unsuccessful pregnancy outcomes occur, we often consider female factor infertility as the only or primary source of the issue. This is followed by invasive testing and medical intervention for women. Meanwhile, sperm is regarded as the key to fertilisation and nothing more. But what role does sperm actually play beyond fertilisation?

Read on to find out how sperm can have a big impact on foetal and pregnancy outcomes and why you may want to test your sperm as one of the first priorities in improving your fertility success.

Words by Katherine Compton


During intercourse, millions of sperm are released within the semen, but only about two million make it to the cervix due to both semen flow back (the loss of excess sperm after intercourse) and the breaking down of many of the sperm by the acidic juices of the vagina.  Resistance, as well as speed, make for the most powerful sperm which will make it to the end of the race. After a journey of attrition through the uterus, only about one thousand sperm make it to the fallopian tube and barely two hundred actually reach the egg.  While it only takes one sperm to fertilise the egg, these extra couple of hundred are vital in secreting enzymes to break down the egg’s defensive barriers (corona radiata and zona pellucida) for the one successful sperm to make it through to fertilise it. Only the nucleus of the sperm penetrates the egg, while the tail and membrane get dissolved. A signal is then released which prevents other sperm from trying to enter the egg. If you take into account how many millions of sperm are lost between ejaculation into the vagina and degradation of the zona pellucida, it is clear why a low sperm count can cause male infertility.

Therefore, in order to fertilise an egg successfully, sperm health needs to be in tip-top shape. To improve sperm quality, quantity and morphology, lifestyle changes are often suggested as adequate fertility treatment, provided there is not a much larger underlying issue of infertility. These lifestyle changes may include measures such as:

  • A regular sleeping pattern with enough hours of sleep
  • Maintaining a healthy, nutrient-rich diet
  • Regularly participating in moderate exercise
  • Taking fertility supplements or a pre-natal 
  • Cutting out toxins such as cigarettes, certain toiletries and haircare products and lowering your alcohol consumption
  • Practising relaxation techniques to reduce stress

Applying these suggestions to your daily routine may not only help with your conception success but will also improve the foetal and pregnancy outcomes of the embryo. If the nucleus that has entered the egg is not in the healthiest condition, pregnancy and foetal difficulties may occur.

Foetal Development

It is often thought that once a sperm has delivered DNA to the egg, that’s its job done – any negative outcomes thereafter are as a result of female factor infertility. But recent studies into epigenetics (gene expression across the same DNA) are proving that this is not the case.

The genes within sperm can be affected by the environment where they were produced, in other words while they were developing in the testicles. This affects the way DNA expression occurs within an embryo, meaning that sperm does affect foetal outcomes and can even pass down trauma to the child produced from that sperm.

For example, if a man were to be under immense stress when producing the sperm that fertilises an egg, the DNA of the sperm may appear normal, but the gene expression will be impacted by this environment and may cause abnormal stress responses within his child. This was discovered in a study which compared the offspring of stressed male mice versus relaxed mice. While the DNA of the stressed versus non-stressed offspring were the same, the environment the sperm was produced in affected the way the DNA processed within the offspring, leading to different characteristic outcomes. The offspring of stressed mouse dads responded abnormally to stressful situations as opposed to offspring produced by stress-free male mice.

In a study conducted on human men, sperm of those who were obese affected the way the gene that controls calorie intake and growth was affected when compared to the sperm of non-obese individuals. This meant that offspring produced by men who were obese while conceiving led to a tendency towards obesity in adulthood for their children. However, the study went a little deeper to see if men who had once been obese previously in their lives still produced the same offspring results as men who were currently obese at the point of conception. The results were that upon losing weight, men who had been previously obese now produced healthy offspring that didn’t have a tendency towards obesity.

These studies prove both that the environment in which sperm is produced can impact foetal development, and also that those who produce sperm have the ability to change and control these foetal outcomes. Taking the right measures to improve your sperm health and conceiving after an appropriate amount of time for these things to take affect could help you to produce healthy offspring with good foetal development.

Pregnancy Outcomes

The quality of the fertilising sperm can greatly impact the outcomes of a pregnancy. After all, 50% of the embryo’s genetics derive from it, making sperm health vital for successful conception.

Semen quality can determine whether or not fertilisation will be achieved and also whether the pregnancy will carry to term and result in a live birth.

40% of all causes of infertility in couples are a result of male factor infertility alone, meaning that medical intervention and testing should be considered for men as a first point of action too.

While speed and quality of sperm can impact conception success, poor sperm morphology can potentially cause miscarriage during the initial stages of pregnancy. However, it is impossible to tell if the morphology of your sperm is adequate without appropriate testing via a consultation with a fertility specialist.

Tests that also offer analysis of DNA fragmentation can be useful for determining the potential pregnancy outcomes of which your sperm are capable. Sperm DNA needs to be intact for a successful conception and for maintaining a pregnancy.

Testing your sperm can determine the potential risk your sperm poses to pregnancy outcomes and foetal development. This can then lead to determining a personal treatment plan to help you conceive. Legacy offers an at-home testing kit for sperm which is currently the most thorough testing kit out there. The Legacy Sperm Analysis looks at the health and quality of sperm by analysing: volume, count, concentration, motility and morphology (which includes sperm DNA fragmentation analysis). This can be a non-invasive, efficient and quick way of getting to the root cause of your potential infertility issues. For $65 off the Legacy Sperm Analysis kit, use code DADLIFE65 at checkout.

To learn more about fertility and ways to improve your chances of conception, subscribe to our weekly newsletter. To speak with others within our community who understand your struggle, download the Fertility Squad app.

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