The concentration of sperm released by men during ejaculation has fallen by 51% over the last 50 years. This is one of the main findings of research carried out by the Hebrew University of Jerusalem, in Israel, and the Mount Sinai School of Medicine, in the United States.
The researchers calculated that in the 1970s, men had an average of 101 million reproductive cells per milliliter of semen. That average has fallen to 49 million in recent times.
In addition to quantity, the evidence also reveals a drop in the quality of the male gametes. The percentage of cells suitable to enter the ovum has been suffering considerable drops in recent decades. “What has the greatest impact on what we see is the loss of sperm motility. Without this attribute, fertilization capacity decreases”, says urologistand andrologistMoacir Rafael Radelli, vice president of the Brazilian Association of Assisted Reproduction.
This scenario of constant worsening is generating an alert signal among health professionals. “This is something worrying, because we see acceleration in this worsening and we do not know exactly where it may stop”. This is confirmed by the doctor Eduardo Miranda, coordinator of the Andrology department of the Brazilian Society of Urology.
In fact, the rate at which men lose sperm has increased in recent years. According to the same study carried out in Israel and the USA, between the years 1970 and 1990, the concentration of gametes fell by 1.16% annually.
Beginning in the 2000s, that rate rose to 2.64%: more than double. And that is a global phenomenon: scientists observed a reduction in the number of gametes in men on all continents. This shows faster falls in Europe, Africa, Central America and South America.
But what is behind this phenomenon? Specialists point to at least 5 causes. The good news is that there are ways to reverse the threats.
The extra kilos promote a series of disadvantages for sperm. The growth of adipose tissue, which leads to fatness, releases inflammatory substances. These directly affect the production of testosterone, one of the most important hormones in the production of male gametes.
Miranda ensures that excess weight also generates what is called oxidative stress. It is a process in which several cells of the organism end up damaged. “In the same way, the obese individual presents more fatness in the genital region, something terrible for spermatozoa”, says the urologist.
The testicles, where reproductive cells are made and stored, must remain 1 to 2 degrees below body temperature to function well. That is why the scrotal bag is outside the body. The point is that this increase in fat overloads the reproductive organs, which stop working as expected. The World Health Organization estimates that 39% of men are overweight in the world, a statistic that helps explain the proportion of sperm in the last 5 decades.
2. Alcohol, cigarettes, vaping (use of electronic cigarettes), marijuana, cocaine, anabolic steroids… Do you know what all these drugs have in common?
All affect the health of the male gametes. “Some of these substances directly damage the germ cells, which give rise to spermatozoa”, summarizes Miranda. Others, however, act indirectly. They affect the production of hormones responsible for stimulating the work of the testicles.
The most cited example among experts is testosterone replacement through pills, gels, and injections, used indiscriminately to gain muscle. “This is a market that has grown insanely and frightfully in recent years”,Radaelli warns. The doctor explains that when this hormone is added indiscriminately, the body understands that there is no longer a need to produce it naturally. As a result, the testicles can even atrophy and the sperm count in the semen ends up at zero, in a condition known in medicine as azoospermia.
3. Sexually transmitted infections
Diseases such as chlamydia and gonorrhea, caused by bacteria, can cause inflammation in the epididymis. This structure connects to the top of the testicles and is responsible for storing sperm. An alteration there, therefore, poses a risk to the survival of the gametes.
The WHO estimates that, in 2020 alone, there were 129 million new cases of chlamydia and 82 million of gonorrhea among men and women. This rate has remained stable or rising in recent decades.
Radaelli adds a third pathogen to the list: the human papillomavirus, also known by the acronym HPV. “It is known that it can also affect the production or even the DNA of the sperm”, he says.
4. Computer on your lap
Remember that story about the testicle needing to be 1-2°C cooler than the rest of the body? Well, studies published in the last decade have revealed that the habit of carrying a laptop on the lap represents an additional risk for the sperm factory. That is because the battery in the device gets hot and can end up “cooking” the sperm.
Miranda points out that other habits related to higher temperatures also pose reproductive risks. This is the case, for example, of long baths in a bathtub with hot water or long days in saunas.
Still in the field of technology, the doctor cites the possible effect of electromagnetic waves, telephone signals and even wireless internet. “In experimental studies, carried out in the laboratory, elements such as Wi-Fi and electromagnetic waves affect sperm,” she reports. “But it is not yet possible to be sure that these technologies really represent harm to these cells”,he ponders.
5. Endocrine disruptors
To round off the list, experts call attention to a series of toxic compounds known generically as endocrine disruptors. The list includes pollutants detected in the atmosphere, as well as plastics and pesticides.
In short, these molecules have a structure very similar to the hormones in our body. With that, in the same way that a key enters a lock, these substances manage to fit into cell receptors and trigger some unwanted processes.
One of these novelties detected in recent studies has to do precisely with male fertility. “But we still don’t know for sure the extent of this problem and there are many studies underway to determine it”, says Radaelli.
Are we going to meet an infertile world from now on?
In addition to environmental and behavioral factors behind sperm drop, there are 2 intrinsic issues that also contribute to the phenomenon. The first of these is genetics. It is estimated that between 10 and 30% of cases of difficulty in having a child have to do with a problem in the male DNA. The second is related to aging and the fact that men seek paternity later and later.
“We know that fertile capacity decreases throughout life. Although the decrease in men is not as pronounced as in women, there is a reduction in hormones that are important for the manufacture of gametes”, she explains. If we consider that the number of spermatozoa has decreased by 51% in 50 years and the speed at which this has been occurring has accelerated in the last 2 decades, is the trend that this number is getting closer and closer to zero?
After all, if this rate of decline continues at current levels, by 2050 the concentration of reproductive cells in semen would be close to zero.
But Miranda does not believe this doomsday scenario will come true. “The tendency is for the situation to get worse, but at some point this process will stall and we will come to a standstill, perhaps with the help of new technologies,” he bets.
Why is it a myth that spermatozoa frantically swim towards the egg during the fertilization process? What to do?
For those who want to have a child, the first step to increasing the chances of success is to make some lifestyle changes. Therefore, they should start reversing the harmful processes for the testicles. This involves, for example, maintaining or losing weight through a balanced diet and regular physical activity. Avoiding or completely avoiding alcohol, cigarettes, and other drugs is also a basic recommendation.
If sex activity is recreational, with occasional partners and without the goal of having a child, it is always worth using a condom to avoid infections such as chlamydia and gonorrhea. People who get vaccinated against HPV in early adolescence are also more protected against this virus and the repercussions it causes in the body. If, even with all these changes in routine, the difficulty in having a child persists, it is worth seeking out a specialist.
According to national and international guidelines, the time to seek a specialized evaluation will depend on the age of the woman. “If you are under 35 years of age, the couple should try to have a child for up to a year, with regular sexual intercourse about three times a week, with monitoring of fertile periods”, Miranda points out.
However, if the couple is over 35 years old, a difficulty conceiving for more than six months should already set off the alarm bell. This is because the reserve of eggs from that age begins to decrease more rapidly. And a 12-month delay in finding answers can represent a very valuable loss of time, say the doctors. “Research needs to involve the couple to discover the possible causes and indicate the best treatments”,Radaelli reinforces.
If the problem is in the male part, specialists usually prescribe vitamin supplements rich in antioxidants, which help protect the testicles. It may also be necessary to regulate hormones through supplementation. “And, of course, it is possible to correct some of the diseases that are at the origin of the problem through drugs and surgery”, says Miranda. “This is the case, for example, of treating bacterial infections with antibiotics and anatomical defects in the reproductive system with surgical interventions”,he concludes.
As a last resort, the couple can resort to assisted reproduction techniques, such as in vitro fertilization.