What Affects Sperm Count?

Heat and technology are just a few factors that can affect or lower your sperm count.

Infertility can affect anyone. Approximately one in 10 couples are infertile, and it has been estimated that factors related to people assigned male at birth contribute to between 20-30% of cases.

People assigned male at birth can possibly produce millions of sperm a day. However, external factors (like temperature) can affect the health of sperm. Here are 10 factors that may affect sperm count and how to reduce potentially reduce your risk of lowering your sperm count.


Human testes cannot function properly to produce sperm unless they can stay cooler than the rest of the body. Specifically, the testicles should be 2 to 4 degrees Celsius (3.6 to 7.2 degrees Fahrenheit) cooler than a person's body temperature to produce quality sperm.

If the temperature of the testicles is raised to 98 degrees Fahrenheit, sperm production stops, according to Hal Danzer, MD, a Los Angeles fertility specialist. "The overall number (of sperm) can be lower, as well as the motility and morphology," said Paul Shin, MD, a urologist in Washington, DC.

Overheating may be resolved depending on what is causing the heat to the testicles (more on that in the sections below).

Hot Tubs

Using hot tubs or saunas may lead to overheating. One study found sauna exposure induces a significant but reversible impairment of spermatogenesis. This process happens at the body's cell level to ensure fertilizing sperm are produced.

According to Dr. Shin, wet heat exposure can affect sperm for a long time. Because sperm takes so long to mature, "any interventions (to reduce exposure) will usually take at least three, if not six to nine, months to show any benefit," said Dr. Shin.

Less exposure to the source of the heat may be helpful. If you are using a sauna or hot tub that is 102.5 degrees Fahrenheit, aim to use them for less than 20 minutes—and less often.


Having a fever might affect sperm. Researchers found that increased body temperature due to fever can affect:

  • Sperm output
  • Motility (movement)
  • Morphology (structure)
  • DNA fragmentation (the breaking of DNA strands that's sometimes linked with low pregnancy rates)

The study also found that fever from SARS-CoV-2 virus infection led to a reversible negative effect on sperm production.

To potentially reduce a fever's effect on sperm, work on ways to break the fever, such as staying cool and resting.


While you do not have to stop using laptops or cellphones, it's good to understand how using these devices may affect sperm count.


Laptops can pose an issue for sperm count when actually used on your lap. Laptops can be a problem because of the increased heat of a person's scrotum from the computer.

However, the same study indicated another problem could be the wireless connection from the laptop. The Wi-Fi radiofrequency radiation (coming from electromagnetic fields) can also affect the quality of sperm.

So, if you're trying to conceive, it may be helpful to use your laptop elsewhere other than on your lap—or at least limit the time you have it on your lap.


The advice varies when it comes to keeping cell phones near the male reproductive organs. One study found that mobile phone use had a negative effect on sperm motility, which can have a negative impact on fertility.

Dr. Shin recommended patients carry their phones in their briefcases rather than pockets to limit radiation exposure. But another study said to carry your mobile device anywhere besides a pocket of your pants.


How fitted your clothing is might play a role in sperm count. For example, research found that men who wore boxers had more concentrated sperm and higher total sperm counts than men who did not wear boxers.

However, participants in that study were seeking fertility treatment, and the authors said that the results could not be applied to people in the general population. "Boxers are better than briefs if a man's sperm count is on the low side. But it probably has little effect if the sperm count is normal," said Dr. Danzer.

However, wearing tight bicycle shorts for an extended period is a bad idea, said Kurt Wharton, MD, a San Francisco OB-GYN specializing in infertility.

The more constricted the pants are, the less hospitable an environment a person creates for sperm production. So, you might consider loose-fitting clothing overall to help sperm quality.

Lifestyle Factors

Sperm count can decrease with the use of different substances. "Tobacco, alcohol, and marijuana can impair sexual function," said Dr. Potter.

Researchers found that cigarette smoking and heavy alcohol intake can deteriorate sperm quality. The study also found that alcohol consumption deteriorates sperm maturity and damages DNA integrity at significantly higher rates than cigarette smoking.

Marijuana can also affect sperm count. Smoking cannabis has been shown to reduce sperm count and function and overall male fertility. One study found that the use of cannabis in males was associated with:

  • Erectile dysfunction
  • Abnormal formation of sperm
  • Testicular shrinking

Dr. Potter has recommended patients limit or avoid these factors when trying to conceive. Doing so might help improve chances for conception.

Cannabis may or may not be legal for medical or recreational use depending on the laws in your state. The effects of cannabis vary from person to person and depend on many variables, including type, dosage, frequency of use, and interactions with current medications. If you are interested in using cannabis in any form, discuss it with your healthcare provider or pharmacist. Unlike prescription medications, cannabis purchased from dispensaries and recreationally is not regulated by the FDA.

Other Conditions That Might Affect Sperm Count

In addition to environmental factors, some bodily conditions may affect sperm.


Blockages that happen in ducts can prevent sperm and semen from mixing. "Whether it's caused by a birth defect, infection, trauma, or vasectomy (a surgical procedure), a blockage prevents the sperm from entering the semen," explained Dr. Potter.

If surgery cannot fix a blockage, assisted reproductive technologies (ART) may help a person with conception.

Genetic Disorders

A person may develop a gene-based disorder that affects their sperm count. "Chromosome abnormalities can cause severely diminished or no sperm production," said Dr. Potter. For example, one form of cystic fibrosis can cause the vas deferens (the tube that carries sperm out of the testes, which produces the sperm) not to form.


A heavier weight can affect sperm count. "Obesity has been associated with increased production of female hormones (estrogen), decreased sperm counts, sexual dysfunction, and infertility," said Daniel A. Potter, MD, a reproductive endocrinologist with the Huntington Reproductive Center in California and fellow of the American College of Obstetricians and Gynecologists.

One study found that individuals who were overweight were 11% more likely to have a low sperm count and 39% more likely to have no sperm in their ejaculate. Those with obesity were 42% more likely to have a low sperm count than their peers of average weight and 81% more likely to produce no sperm.

You may be able to increase your sperm count and sperm concentration by losing weight. What's more, if you maintain the weight loss, you may also maintain those increases in count and concentration.

Varicoceles (Enlarged Scrotal Veins)

Varicoceles are enlarged veins in the scrotum, usually on the left side. These veins can lead to potential issues with a lower sperm count and testosterone.

Healthcare providers may recommend varicocele repair, a procedure that corrects enlarged varicose veins in the scrotum. This is done surgically or via embolization, a nonsurgical procedure using a catheter.

Though there is little proof that fertility improves after varicocele embolization, some providers believe the surgery may improve semen quality. However, surgery cannot help varicoceles that have been present long-term.

Other Factors

Sperm can also be affected by:

  • Anti-sperm antibodies
  • Hormonal imbalance
  • Testicular cancer
  • Undescended testicles
  • Sexual problems

A Quick Review

Different factors can affect a person's sperm count. These may be lifestyle factors, like using a hot tub, or factors out of a person's control, like genetic disorders. For some factors, some ways might improve sperm count.

But talk with a healthcare provider if you're having issues with fertility to determine what treatment options may be best for you.

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19 Sources
Health.com uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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