5 things you need to know about sperm quality

Around 40% of Danish men have reduced sperm quality. We asked molecular biologist Anne Sofie Rex to answer five of the most frequently asked questions about impaired sperm quality.

1. Does sperm quality change and why?

Sperm quality can change. If you have a low sperm count, it is difficult to get a lot more, but you can improve the quality of the sperm you have.

Exercise regularly and try to maintain a healthy BMI. One way to do this is through lifestyle choices: You can increase your intake of fruit, vegetables, whole grains, fish and poultry. Avoid smoking (or snuff tobacco) and eat only moderate amounts of red meat, sweetened products (both artificial and sugar-sweetened) and caffeinated drinks. Asa general rule, you should also follow the health authority's recommendations on alcohol.

Sperm quality can also deteriorate, for example, if you lead a less healthy lifestyle. Diseases such as varicocele, diabetes or circulatory disorders can also negatively affect sperm quality. There is also a risk that some types of medication (for example, SSRIs or rheumatic drugs) can reduce sperm rates.

Untreated STDs, such as chlamydia, can risk closing off the sperm duct so that you produce quality sperm, but the closure means they can't get out during ejaculation.

External and internal heat (e.g. fever) can cause temporary deterioration in sperm quality. However, the sperm quality will improve again after three months. Working with toxic substances/chemicals and not paying attention to occupational health and safety rules can also impair sperm quality.

2. What does reduced sperm quality mean?

The WHO sets the cut-off point for reduced sperm quality. The sperm quality of a group of men who have impregnated their partner within a year is studied. The bottom 5% were judged to have reduced quality.

You have reduced sperm quality if:

- The total number of sperm cells is less than 39 million.

- The concentration is less than 15 million/ml.

- The volume is less than 1,5 ml.

- Less than 40% of the sperm cells are motile.

- Less than 32% of the sperm cells are moving forward.

- Less than 4% have standard shape (morphology).

For comparison, the average values for a sperm sample are:

- 255 million sperm cells in total in the sample.

- A concentration of 75 million/ml.

- A volume of 3.7 ml.

- 61% of sperm cells are motile.

- 55% of sperm cells are moving forward.

- 15% of sperm cells have a standard shape (morphology).

3. Do you risk having a boy with reduced sperm quality if you have it?

It depends on the cause of infertility. Up to 15% of male infertility is estimated to be due to genetic factors - including chromosome abnormalities, Y-chromosome microdeletions and single gene defects. There are up to 4,000 genes involved in spermatogenesis. This often includes severely reduced quality, no sperm, or poor morphology/movement.

Some of these are hereditary - for example, Y microdeletion, where a little of the Y chromosome is missing in the male. As male children inherit their entire Y chromosome from their father, they will also inherit the deletion. There are also several inherited single-gene mutations. These have different effects on the degree of infertility.

Another genetic condition that is not inherited is Klinefelter syndrome. Here the male has XXY instead of XY, and this affects spermatogenesis. However, the sperm cell will still carry only a single X or Y, passed on to the child.

4. Does your lifestyle affect your sperm quality?

Yes, lifestyle significantly affects sperm quality, as discussed in answer to question 1. If you want to do something to change your sperm quality, you can do so through diet (increasing your intake of fruit, vegetables, whole grains, fish and poultry) and by avoiding smoking, large amounts of red meat, sweetened products and caffeinated drinks. You need a healthy BMI.

5. Can reduced sperm quality affect the foetus? For example, causing pregnancy loss or something else?

Yes. There is a lot of talk about DNA fragmentation in sperm. This cannot be seen from the number or appearance of the sperm cells: you have to "look inside" the sperm cell.

Here, it has been found that if there is a high degree of DNA fragmentation in the sperm, it will be more challenging to achieve spontaneous pregnancy and pregnancy after insemination treatment. It has been found that fertilisation is as good after ICSI treatment and almost as good after IVF treatment compared to sperm samples with low levels of DNA fragmentation. Still, unfortunately, it is also found that a proportion of these pregnancies are lost. The theory is that the egg will try to repair the damage to the sperm. If this fails, the woman's body will reject the pregnancy again.

Studies are often carried out to examine the development of children conceived by fertility treatment. In most cases, the development is the same as in children conceived by sexual intercourse. A few studies have seen slightly more children with developmental disorders or other diseases conceived by older fathers or fathers with increased DNA fragmentation.