Male fertility testing: what semen analysis reveals

About half of all infertility cases involve a male factor, yet most men never get properly tested. Guidelines only call for a semen analysis after a full year of trying to conceive without success, so couples often spend months or years chasing explanations on the female side alone. A urologist from Stanford's male fertility program and a reproductive endocrinologist who runs a private fertility practice in Austin recently sat down to explain what a semen analysis actually shows, why it is being skipped, and why sperm health may say more about a man's future than most people realize.

Half of infertility involves the male partner

Roughly a third of infertility cases are solely female, a third solely male, and a third involve both partners. Despite that, surveys suggest male partners go completely unevaluated in up to a third of infertile couples. One doctor described a couple who tried for a year and a half before testing revealed the male partner, a cystic fibrosis carrier, had zero sperm reaching his ejaculate. A basic semen analysis would have caught this immediately and changed their entire timeline. Being able to ejaculate normally tells you nothing about sperm concentration, movement, or DNA health.

What a semen analysis actually measures

A standard semen analysis looks at several parameters together:

• Volume, the amount of the ejaculate
• Concentration, how many sperm are present per milliliter
• Motility, how well the sperm move
• Morphology, the shape of the sperm
• pH and other extraneous markers

None of these can be inferred just from a normal erection or a normal testosterone level. Total motile sperm count, a calculated combination of volume, concentration, and motility, is considered one of the most useful single numbers, with around 40 million typically associated with the best odds of conceiving.

DNA fragmentation, the test most men never get

DNA fragmentation testing looks at oxidative stress and DNA damage inside the sperm head rather than just shape or movement. It is not part of a routine semen analysis. The American Society for Reproductive Medicine recently added it to its recommended workup after two or more pregnancy losses, since fragmented sperm is linked to chronic inflammation, poor diet, obesity, smoking, alcohol, cannabis, and exposure to endocrine disrupting chemicals.

Lifestyle factors that affect sperm quality

Several modifiable factors came up repeatedly:

• Cannabis use, especially daily, lowers sperm quality and motility and is linked to higher miscarriage rates even when the female partner does not use it
• Heat exposure from saunas, hot tubs, baths, and heated seats interferes with the testicles' ability to stay cool for sperm production
• Microplastics were found in every tested human and dog testicle in one recent study and are considered an emerging concern
• Cycling more than five hours a week is associated with lower sperm counts
• Unsupervised testosterone therapy shuts down the brain's signal to produce sperm and can sometimes cause irreversible damage
• Sleep matters enormously: every hour less of sleep is linked to worse sperm parameters and a longer time to pregnancy

Interestingly, a high sperm count appears to outweigh obesity or smoking in relative risk terms, though doctors were clear this is not a reason to smoke.

Sperm health as a window into future health

Doctors increasingly describe semen parameters as a sixth vital sign. A Danish study followed men for thirty to fifty years after a single semen analysis and found that every parameter, including volume, concentration, and total sperm count, correlated with age at death. Men with lower semen quality also show higher rates of psoriasis and rheumatoid arthritis, both before and years after their semen analysis. Sperm genes even influence placental development, affecting risks like preeclampsia and preterm birth. Since spermatogenesis takes about three months, lifestyle changes can show up in a new semen analysis in as little as three months, a genuinely actionable window most men are not told about.

Home testing versus clinic testing

Testing options vary widely. Some at-home kits give a simple yes or no on whether sperm are present. Others report several parameters through an app. The most complete option is mailing a sample to a CLIA-certified lab for a full panel, including DNA fragmentation, without ever visiting a clinic. Not all tests are equal, so it is worth checking exactly which parameters a given test reports before assuming a normal result means everything is fine.

What men can do starting today

If a couple has been trying for eight months or more without success, both partners should get evaluated, not just the woman. For men specifically, the doctors recommend:

• Getting a semen analysis and, if there have been pregnancy losses, asking about DNA fragmentation testing
• Eating an anti-inflammatory diet rich in fruits and vegetables while cutting processed foods
• Exercising moderately, since both extremes, sedentary habits and elite endurance training, appear to lower sperm counts
• Maintaining a healthy weight and prioritizing seven or more hours of sleep
• Avoiding daily cannabis, cutting back on saunas and hot tubs, and reducing exposure to plastics
• Talking to a doctor before starting testosterone therapy if future fertility matters

None of these changes need to be perfect or extreme. Together, they meaningfully shift the odds within a single three-month cycle, and they double as some of the same habits linked to lower long-term risk of heart disease and other chronic conditions. Getting tested early simply gives couples the data to make informed decisions instead of waiting a year to find out what could have been addressed from the start.