When Does Sperm Weaken?

Although men never stop producing sperm throughout their lives, sperm production does begin decreasing after age 35. Motility, volume and genetic quality of sperm of older men are less likely to achieve a successful pregnancy even in younger women. In addition, there is a risk that older men may pass on chromosomal and genetic defects due to reduced genetic quality of their sperm. Alternately, some research has found that sperm of young men under 20 years of age has been linked to increases in certain birth defects such as Down syndrome, cystic kidney and neural tube defects.

Factors Affecting Sperm Quality
Environmental and health stressors can impact the quality and motility of sperm. These include:

Excessive Heat

Sperm are sensitive to heat and will die if exposed to higher temperatures without relief. A man’s body has natural compensatory mechanisms to avoid losing sperm to extreme heat, such as letting testicles hang down further away from the body or relaxing the cremaster muscle (a muscle covering the testes). Perspiring and countercurrent exchanges of blood cooling down heated blood that is flowing around the testes are other ways the body tries to protect sperm from heat.

Sauna sessions, bathing for more than 15 minutes in hot water, lying in tanning beds and even placing laptop computers over the groin can raise body temperature enough to impair sperm quality. Contrary to long-held belief, there is no clinical evidence supporting the claim that wearing tight underwear or jeans decreases sperm quality.

Severe Physical Trauma

Getting struck in the testicles will not diminish sperm quality or the quality of existing sperm cells. The scrotum and tissues called the tunica vaginalis do a good job of protecting the testes from minor to moderate external pressure. However, if a blow is hard enough to crush capillaries supplying blood to sperm-producing tissues, it could result in temporarily or permanently affecting a man’s ability to produce sperm in the damaged testicle.


Selective serotonin reuptake inhibitors (SSRIs) prescribed for depression, anxiety or obsessive-compulsive disorder my lower sperm count in some men. Tetracycline, penicillin and other antibiotics have been shown to suppress production of sperm as well. Marijuana (specifically, THC) is known to interfere with motility of sperm and reduce their ability to fertilize an egg. Other drugs that could weaken sperm strength include opioid analgesics (pain pills), calcium channel blockers, statins and phosphodiesterase inhibitors prescribed to treat erectile dysfunction and heart problems.

Anabolic Steroids

Men using anabolic steroids for muscle enhancement may not notice a reduced sperm count right away but long-term use of steroids will weaken sperm and decrease the amount of viable sperm. Additionally, anabolic steroids may cause erectile dysfunction, low libido and even shrink the testicles.

Environmental Toxins

Men who are consistently exposed to specific mutagens have been found to have weakened sperm quality. These chemical include:

Plutonium (interferes with metabolism of zinc and causes genetic damage)
Ethylene oxide (a powerful sterilizer)
Cadmium (damages Sertoli cells and prevents spermatogenesis)
Lead and mercury (may cause abnormal spermatozoa)
Pesticides and solvents such as toluene, benzene and styrene can reduce sperm count and damage existing sperm)

What is a Semen Analysis?
To determine if a man has problems with sperm count, quality or motility, a semen analysis is necessary to analyze the shape of sperm, its ability to move and how many sperm are contained in one ejaculation. Also evaluated during a semen analysis is the man’s white blood cell count, fructose level in the semen and the pH and volume of semen. Depending on the issues found with sperm, Viera Fertility may recommend a treatment plan to increase sperm quality so that conception can be achieved with the man’s partner.

When weakened sperm or reduced sperm counts cannot be modified, we offer a variety of state-of-the-art assisted reproductive technologies such as IVF and IUI to significantly increase a couple’s chance of having a child. Call Viera Fertility today to schedule a consultation appointment with our fertility doctor.