It’s something that many of us will take for granted: have sex, get pregnant. However, it’s not always so straightforward. Infertility is a growing problem worldwide, affecting 1 out of every 8 couples. It’s estimated that about 1 in every 3 cases is due to the male partner alone. Although infertility can be due to a variety of conditions, sperm quality is usually a good predictor of fertility.
What is sperm quality?
Sperm quality refers to sperm’s ability to accomplish fertilization. This ability is impacted by two, interconnected factors: sperm motility and sperm morphology, as well as by the health of the DNA carried by the sperm.
Motility refers to the ability of the sperm to move or “swim,” which is essential for them to move through the female reproductive system and fertilize the egg. Progressive motility is the best type of movement that can be seen in sperm testing—that means the sperm move forward in straight lines or in large circles, as opposed to in small tight circles or along erratic paths.
Morphology means the sperm’s structure or shape, which is ideally:
- the tail, made of protein fibers, which helps it “swim” toward the egg
- the midpiece, or body, which contains mitochondria to power the sperm’s movement
- the head, which houses the nucleus where the sperm’s precious cargo—genetic information—is stored, as well as the acrosomal vesicle, a tiny structure at the tip of the sperm full of enzymes that helps the sperm penetrate the egg by digesting proteins and sugars on the surface of the egg.
This shape is important because it impacts a sperm’s ability to travel to and penetrate and fertilize an egg.
Each sperm cell contains 23 chromosomes, or molecules of DNA, the material that guides the growth and development of the entire human body. This is half the number of chromosomes in a typical human cell; sperm cells are known as “haploid” cells. The egg contains the other half. Together, they create a fully realized cell of 46 chromosomes (known as a “diploid” cell), which then divides to become all of the other cells in the body.
So, as you might imagine, the integrity of genetic material in sperm is essential for successful fertilization and normal embryo development. Sometimes, that DNA can become damaged, broken, or otherwise abnormal, known as sperm DNA fragmentation. DNA fragmentation directly correlates to lower fertility in men, and is also linked to recurrent pregnancy loss (two or more consecutive miscarriages).
DNA fragmentation can be caused by many factors, including age, fever/illness, smoking, and exposure to toxins. Learn more in our guide to DNA fragmentation.
Sperm quality vs. quantity
The other half of the sperm equation is sperm quantity, or sperm count/concentration. Sperm count is the total number of sperm in a particular quantity of semen, the fluid that carries sperm out of the penis. Sperm concentration refers to how densely packed those sperm are within the semen. For example, a sample may include 3 milliliters of semen and a total sperm count of 45 million; that would be a concentration of 15 million sperm per mL.
Sperm quantity and sperm quality are separate factors; a high sperm count isn’t entirely helpful to fertility if most of those sperm are misshapen, can’t swim properly, or carry damaged DNA. But sperm quality issues and low sperm count can be caused by some of the same things, including exposure to toxins or chemotherapy, smoking, and hormone imbalance.
What affects sperm quality?
These are just a few of the most common factors affecting sperm quality:
As a man ages, his sperm motility decreases (according to one study, on average about .8% per year). Additionally, he has lower numbers of sperm with normal morphology—research indicates that normal sperm morphology declines .2–.9% per year, resulting in a 4–18% decrease in normal morphology over a 20-year period. And finally, the sperm of older men is more likely to have higher rates of DNA fragmentation, as well as additional genetic mutations that can lead to schizophrenia, autism, and more. The best way to prevent the issues associated with aging sperm is to freeze your sperm at a younger age. Learn more about sperm freezing.
Smoking, drug and alcohol consumption, diet, exercise, weight, sleep, stress, what type of underwear you wear, and even how often you soak in a hot tub can all impact sperm quality, including morphology, motility, and DNA fragmentation. The good news? Your body is making sperm constantly—so if you make a lifestyle change for the better, you could see sperm quality improvements in as little as two months. Learn more in our guide to sperm improvement.
Certain medications, such as testosterone, anabolic steroids, SSRIs, chemotherapy drugs, opiates, and NSAIDs, may have an impact on sperm quality and sperm production. Whether this impact is reversible depends on the type of medication, dosage, and how long the drug is taken. Additionally, a recent history of infection, illness, and fever can affect sperm quality, but in most cases, the effect is only temporary.
A history of exposure to toxins known to impact sperm quality, such as lead, pesticides, hydrocarbons, PCBs, cadmium, diesel exhaust, petrochemicals, and solvents, is twice as prevalent among infertile men as it is among healthy men. While the toxins in everyday household products may be damaging due to long-term contact, we’re typically most concerned about those who are exposed to toxins through their occupations—those who work in agriculture and herbicides, plastic production, and the military have been demonstrated to have worsened sperm parameters.
Testing your sperm quality
Sperm count and sperm quality (morphology and motility) can be tested with a semen analysis. This test involves providing a semen sample, collected via masturbation, to a lab. There, it will be examined under a microscope to determine your sperm count/concentration, what percentage of your sperm are motile, and your ratio of properly formed sperm.
The test can be done in a fertility clinic or urologist’s office, or can be done from the comfort and privacy of home with a mail-in sperm testing kit, like we offer. The results of your semen analysis will tell you which of your sperm parameters are normal, and which (if any) are abnormal. The Legacy semen analysis report also includes personalized recommendations to improve sperm quality, based on your lifestyle.
DNA fragmentation testing
A typical semen analysis doesn’t test the genetic health of sperm. A more in-depth test, such as a sperm chromatin structure assay (SCSA), is required to evaluate genetic damage within sperm.
Learn more in our Guide to Sperm Testing.
How to improve sperm morphology, motility, and genetic health
There are many fairly simple lifestyle changes that can improve factors associated with sperm quality:
Start an exercise regimen.
Simple, low-intensity workouts (such as walking, biking, or jogging) have a considerable benefit for sperm quantity and quality. Learn more about exercise and sperm health.
Improve your diet.
A balanced, Mediterranean-style diet rich in fruits, vegetables, fish, and nuts—and low in soy products, processed meats, and trans fats—is associated with improved sperm quality.
Quit smoking/reduce drinking.
Alcohol can dampen testosterone production, and negatively affects all aspects of your sperm such as count, concentration, and morphology. Smoking can be especially bad for sperm morphology, creating genetic defects that lower sperm quality. Learn more about smoking and sperm health.
Get enough sleep.
Chronic sleep deprivation (less than 6 hours a night) reduces testosterone levels, lowers sperm count and motility, and increases levels of anti-sperm antibodies, further damaging your sperm.
Avoid certain drugs.
Examples include testosterone, anabolic steroids, SSRIs, chemotherapy drugs, opiates, NSAIDs, and any other medication that has an impact on sperm quality.
After making these changes, you’ll want to retest with another semen analysis to see if your efforts have had a measurable improvement on your sperm quality. Remember that the process of making sperm takes around 74 days, so you’ll want to keep up your new habits for 2–3 months before retesting.
Further reading: Legacy’s Guide to Sperm Improvement.
- E. Sloter et al. “Quantitative effects of male age on sperm motion.” Human Reproduction, 2006.
- L. Bujan et al. “Sperm morphology in fertile men and its age related variation.” Andrologia, 1988.
- Victor Pino et al. “The effects of aging on semen parameters and sperm DNA fragmentation.” JBRA Assisted Reproduction, 2020.
- Pravesh Kumar Bundhun et al. “Tobacco smoking and semen quality in infertile males: a systematic review and meta-analysis.” BMC Public Health, 2019.
- Jaime Mendiola et al. “Exposure to environmental toxins in males seeking infertility treatment: a case-controlled study.” Reproductive BioMedicine Online, 2008.
- Paul Claman, MD. “Men at Risk: Occupation and Male Infertility.” Sexuality, Reproduction & Menopause, 2004.