Men with strong sperm live longer

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COPENHAGEN — Men with high-quality sperm tend to live nearly three years longer than those with poor semen quality, according to landmark research that followed more than 78,000 men for up to five decades. This discovery suggests that reproductive health may serve as a window into a man’s overall health and longevity.

Published in Human Reproduction, this Danish study is the largest and longest of its kind. The research demonstrates a clear pattern: as semen quality improves, the risk of premature death decreases, regardless of education level or pre-existing health conditions.

“Men with a total motile sperm count of >120 million could expect to live 80.3 years, compared to 77.6 years among men with a total motile count of >0–5 million,” the researchers report. This 2.7-year difference persisted even after accounting for various factors.

“We calculated the men’s life expectancy according to their semen quality and found that men with the best quality could expect to live two to three years longer, on average, than men with the lowest semen quality,” explains Dr. Lærke Priskorn, senior researcher at Copenhagen University Hospital—Rigshospitalet and lead author, in a statement. “The lower the semen quality, the lower the life expectancy. This association was not explained by any diseases in the ten years before semen quality assessment or the men’s educational level.”

Beyond Previous Research

Earlier studies had hinted at connections between male fertility and health outcomes, but most only looked at basic markers like whether a man had fathered children or received an infertility diagnosis. This research advances our understanding by directly measuring multiple aspects of semen quality and following participants for decades—some for nearly half a century.

The research team analyzed data from 78,284 men who had their semen assessed between 1965 and 2015 at a public laboratory in Copenhagen. These men had been referred for semen analysis due to self-reported couple infertility, resulting in a study population with a wide range of semen quality.

Researchers measured semen volume, sperm concentration, the proportion of motile sperm, and the percentage of normally shaped sperm. From these measurements, they calculated total sperm count and total motile sperm count, providing a comprehensive picture of both quantity and quality.

A Clear Pattern Emerges

By linking semen data to Denmark’s national health registers, researchers tracked mortality outcomes for a median of 23 years, with some men followed for as long as 45 years. During this time, 8,600 deaths occurred among the study participants.

The analysis revealed a consistent pattern: men with better semen parameters had lower mortality rates across the board. Importantly, this wasn’t limited to comparing fertile versus infertile men—the relationship persisted across the entire spectrum of semen quality, extending well into ranges considered normal.

While medical guidelines consider sperm concentrations of 16 million per milliliter adequate for fertility, the mortality benefit continued to improve at levels far above this threshold. This suggests that what fertility specialists deem “sufficient” for reproduction may not necessarily reflect optimal health.

Oxidative Stress & Sperm Quality

What could explain the relationship between reproductive health and longevity? The findings prompt questions about underlying biological mechanisms that might influence both sperm quality and overall health.

In an accompanying editorial in Human Reproduction, Distinguished Emeritus Professor John Aitken from the University of Newcastle, Australia, calls the study a “landmark” publication and proposes oxidative stress as a potential common denominator.

Oxidative stress occurs when there’s an imbalance between damaging free radicals and protective antioxidants in the body. This imbalance can harm cells throughout the body, including sperm cells, and plays a known role in aging.

“Any factor (genetic, immunological, metabolic, environmental or lifestyle) that enhances overall levels of oxidative stress, could reasonably be expected to drive changes in the semen profile and subsequent patterns of mortality,” writes Professor Aitken. He also suggests this mechanism might help explain links between pregnancy complications and female mortality, noting that “circulating antioxidant levels are generally higher in women than men, just as their telomeres are usually longer.”

Implications for Men’s Health

“We need to better understand the association between semen quality and men’s general health,” says Dr. Niels Jørgensen, chief andrologist at Copenhagen University Hospital and study co-author. “However, this study suggests that we can identify subgroups of men with impaired semen quality who appear healthy at the time of semen assessment but who may be at increased risk of developing certain diseases later in life.”

Jørgensen emphasizes, “Thus, fertility evaluations, which are typically conducted when men are relatively young, could provide an opportunity for detecting and mitigating the risks of other health problems in the longer term. In the current study, we did not analyze whether poor semen quality was associated with earlier deaths from particular causes, such as cancer or heart disease, and this is something we will be studying in the future. Using other groups of men, we will also try to identify relevant biomarkers that can help recognize subgroups of men at increased risk. This is key to initiating relevant prevention strategies.”

For men generally, these findings highlight reproductive health as an important component of overall wellness—not just for those trying to conceive. While the research does not establish causality (improving semen quality wouldn’t necessarily extend lifespan), it indicates that many factors affecting general health also impact reproductive function.

Study Nuances and Future Directions

An interesting pattern emerged regarding men with no sperm at all (azoospermia). While this group showed elevated mortality compared to men with excellent semen quality, their risk was slightly lower than men with very low sperm counts. This likely reflects the mixed nature of azoospermia—some cases result from blockages with otherwise normal sperm production, while others indicate more fundamental reproductive problems.

The study had notable strengths and limitations. Its unprecedented size and decades-long follow-up provide robust data. However, lifestyle factors like smoking, weight, and exercise weren’t directly measured, though education level served as a partial proxy. Additionally, the focus on Danish men may limit global applicability, and health assessments were limited to hospital diagnoses, potentially missing conditions managed by primary care physicians.

Future research will explore whether poor semen quality correlates with specific causes of death and will aim to identify biomarkers that could help recognize men at the highest risk for health problems.

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