In 50% of cases where pregnancy fails to occur, the cause is found to be with the male partner. In men, there is almost never a case of total infertility, but in most cases, subfertility (reduced fertility). This is usually because the concentration and motility of the sperm cells are not optimal.
This limits the fertilizing ability of the sperm cell if it is lower than normal, which can be determined through various tests. The simplest way to get an indication of sperm quality is with a home test like Swimcount.
Sperm Production
At birth, only precursors of sperm cells, also called stem cells, are present in the testicle. Spermatogenesis, or sperm production, begins from puberty. Mature sperm cells are discharged and, together with additional fluid, end up in the ejaculate. The sperm cells and the fluid together form the semen.
This is a continuous maturation process, where the development of a sperm cell takes about 75 days. External factors such as fever, an unhealthy lifestyle, or (viral) infections can negatively influence the maturation process.
What Should a Sperm Cell Be Able to Do?
After ejaculation, the sperm cells must travel a distance of 12 to 17 cm: from the cervix to the fallopian tube where fertilization takes place.
After ejaculation, sperm cells normally have the ability to fertilize for about 48 hours. (This is not the case if the semen is produced and processed in the laboratory.)
During the fertile period of the woman, the vagina becomes less acidic and the optimal environment for sperm cells is created so that they can easily move to the uterus. This is done by extra production of cervical mucus.
To be able to fertilize an egg, the sperm cells must undergo a change (capacitation). This ensures that the sperm cell can swim in a straight line, which is important for fertilization.
The acrosome reaction is an important process to dissolve the protective shell of the egg. The sperm cell can dissolve this shell because the head of the sperm cell contains certain enzymes.
Then the sperm cell binds to the wall of the egg with the help of specific proteins.
This allows the sperm cell and egg to fuse and share genetic material. This is an important and complex step in fertilization. Once the egg and sperm have fused, we call it a zygote. This is about 1 day after ejaculation or insemination.
It is therefore clear that sperm cells have an important function and must be in good condition to independently fertilize an egg. The quality of the sperm can therefore influence the development of the embryo.
Reduced Sperm Quality
Problems with male fertility can have various causes. In many cases, the quantity and motility of sperm cells are not sufficient, preventing the egg from being fertilized. Poor sperm quality is usually due to a disorder in sperm production. The exact cause of this is often unclear.
Possible causes of reduced sperm quality:
- Inflammation in the testicles or epididymis (e.g., due to mumps/orchitis).
- Surgery
- Radiation or chemotherapy
- The presence of varicocele, a type of varicose vein in the scrotum.
- Lack of fertilizing ability
- Antibodies on the sperm cells
- Genetic factors
- Use of certain medications or anabolic steroids
- Unhealthy lifestyle: smoking, drug or alcohol use, obesity.
In most cases, there is no clear cause.
No Fertilizing Ability
It can happen that the semen looks ‘normal’ according to the results of a semen analysis, but that it has no fertilizing ability. This only comes to light during IVF treatment. This occurs very rarely.
Antibodies
Sometimes antibodies are present on the sperm cells. This causes the sperm to lose its ‘progressive’ motility, meaning they do not move in a straight line. Fortunately, not all cases of antibodies have a negative effect on fertility. Antibodies can be detected, but they cannot be explained in all cases.
Hereditary Factors
Hereditary factors can play a role in reduced fertility. In cases of severely deteriorated sperm quality or even absence of sperm cells, abnormalities in DNA are sometimes found. If a genetic cause is found, there may be an increased risk of miscarriage or a child with congenital abnormalities. Blood tests can determine if hereditary factors are present.
Other factors with a negative effect on sperm quality:
- Excessive alcohol consumption
- Smoking and drugs.
- A temperature that is too high in the testicles
- Fever or a viral infection can temporarily cause poor sperm quality.
- Working with chemical or radioactive substances, pesticides, lead, ionizing radiation (e.g., X-rays). Risk groups include painters and nursery staff.
- Stress can be a cause of temporarily reduced sperm production.
- Ejaculating too frequently (multiple times per day) This does not necessarily have a negative effect on quality.
- Ejaculating too infrequently can lead to a decrease in sperm motility. An optimal amount of sperm cells is obtained by ejaculating once every two to five days.
Absence of Sperm Cells
It can also occur that no sperm cells are found in the ejaculate at all. There is increasing evidence that the cause is a genetic problem. In these men, the chance of finding sperm in the testicle is about 50%. The correct diagnosis can be made through various blood tests or a testicular biopsy.
There are two forms:
Obstructive azoospermia: due to absence of the vas deferens or a blockage in the vas deferens
Non-obstructive azoospermia: due to a problem in the production of sperm cells.
