London Daily

Focus on the big picture.
Monday, Jun 30, 2025

Scientists believe these are the reasons for falling sperm counts

Scientists believe these are the reasons for falling sperm counts

Researchers have looked at nearly 27,000 studies to identify the biggest factors causing sperm damage. This is what they found.

Men’s reproductive capacity has fallen drastically in recent decades - and a new analysis of thousands of studies has revealed the factors that pose the biggest risk to sperm quality.

Sperm counts around the world have halved over the past 50 years, with the pace of decline more than doubling since 2000, according to recent research on male fertility.

Researchers at Semmelweis University in Hungary have dug deeper into the findings of nearly 27,000 studies to determine the biggest causes of deterioration of sperm cells, and found pollution, smoking, age, and certain health conditions to have the greatest effect.

Their findings were published in the journal Reproductive Biology and Endocrinology.

The functionality of sperm cells is tested by “DNA fragmentation analysis,” currently the only evidence-based test to make the determination, explained Dr Zsolt Kopa, head of the Andrology Centre at the Department of Urology at Semmelweis University.

"It examines their DNA content, namely the proportion of intact or fragmented genetic material in the sperm. The more fragmented the DNA, the less the sperm’s ability to fertilise; also, it can increase the risk of miscarriage," he said.

The research comes amid growing concern about the dramatic fall in male reproductive capacity. Research published late last year in the journal Human Reproduction Update showed that sperm counts worldwide have halved over the past five decades.

Professor Hagai Levine, one of the researchers behind that particular study, called it a "canary in a coal mine," adding that "we have a serious problem on our hands that, if not mitigated, could threaten mankind’s survival".


Age, pollution, lifestyle


The Semmelweis scientists searched three international databases for previously published studies, finding 26,901 articles, and using 190 for their meta-analysis. All were published between 2003 and 2021, mostly in Europe, the US, and Asia, with some in Africa and Australia.

Data of thousands of men treated in infertility clinics were compared - and some results surprised even the researchers.

"Based on previous research, we expected that the quality of sperm cells starts to deteriorate significantly after age 40, but our meta-analysis suggests that this age could be much higher," said Dr Anett Szabó, a PhD student and first author of the Semmelweis publication.

"But, of course, this is not to say that it’s worth waiting to start a family as other important parameters can also deteriorate with advancing age".

The researchers did find that the studies demonstrated smoking could increase DNA fragmentation by an average of 9.19 per cent compared to non-smokers.

Alcohol, and body weight, didn’t have a clinically significant role in the fragmentation of the genetic material. A tendency that more alcohol and higher body weight lead to more considerable fragmentation was detectable, however.

Pollution had a clear detrimental effect on sperm quality. Two of the studies reviewed showed the effect on sperm in a region in Italy with particularly high environmental pollution, while another showed similar effects on police officers directing traffic at a busy junction.

The meta-analysis found that various factors, such as air pollution, the exposure to pesticides or insecticides, increased sperm DNA fragmentation by an average of 9.68 per cent.


Underlying health problems


Certain health problems were also shown to be a factor. Varicocele, which is the dilation of the veins in the spermatic cord, was found to increase fragmentation by an average of 13.62 per cent while reduced glucose tolerance also affects it to a similar extent.

Tumours, meanwhile, can cause an 11.3 per cent increase in fragmentation.

Infections such as Chlamydia and HPV did not appear to impair sperm quality, but bacterial or other STIs did show a slight increase in fragmentation.

"In recent years, there has been an increasing demand to measure men’s fertility with functional, objective parameters, in addition to the classical quantitative and qualitative characteristics," said Kopa.

"DNA fragmentation can be of outstanding importance, and the test was officially included in the international guidelines in 2021. However, there are still no official standards on the values of infertility and fertility," he added.

"In clinical practice, we use only consensus values. Generally, a fragmentation below 25 per cent can be considered optimal; above this, the chance of spontaneous conception decreases. Beyond 50 per cent, the success rate of IVF is also lower".

The experts added that quitting smoking, getting enough exercise, or eating more healthily could be a good start for people who are planning to try for a child.

Comments

Oh ya 2 year ago
Not a surprise seeing all the chemicals that are put into food now days. Compared to years ago our food is not very nutritionist. Garbage in garbage out
A friend gave me some organic tomatoes the other day i could not believe how good they tasted, like i remember from years ago as a kid. After i finished them i bought some from Price Smart and they were bland and tasteless

Newsletter

Related Articles

0:00
0:00
Close
Robots Compete in Football Tournament in China Amid Injuries
Trump Administration Considers Withdrawal of Funding for Hospitals Providing Gender Treatment to Minors
Texas Enacts Law Allowing Gold and Silver Transactions
China Unveils Miniature Insect-Like Surveillance Drone
OpenAI Secures Multimillion-Dollar AI Contracts with Pentagon, India, and Grab
Marc Marquez Claims Victory at Dutch Grand Prix Amidst Family Misfortune
Germany Votes to Suspend Family Reunification for Asylum Seekers
Elon Musk Critiques Senate Budget Proposal Over Job Losses and Strategic Risks
Los Angeles Riots ended with Federal Investigations into Funding
Budapest Pride Parade Draws 200,000 Participants Amid Government Ban
Southern Europe Experiences Extreme Heat
Xiaomi's YU7 SUV Launch Garners Record Pre-Orders Amid Market Challenges
Jeff Bezos and Lauren Sanchez's Lavish Wedding in Venice
Russia Launches Largest Air Assault on Ukraine Since Invasion
Education Secretary Announces Overhaul of Complaints System Amid Rising Parental Grievances
Massive Anti-Government Protests Erupt in Belgrade
Trump Ends Trade Talks with Canada Over Digital Services Tax
UK Government Softens Welfare Reform Plans Amid Labour Party Rebellion
Labour Faces Rebellion Over Disability Benefit Reforms Ahead of Key Vote
Jeff Bezos and Lauren Sánchez Host Lavish Wedding in Venice Amid Protests
Trump Asserts Readiness for Further Strikes on Iran Amid Nuclear Tensions
North Korea to Open New Beach Resort to Boost Tourism Economy
UK Labour Party Faces Internal Tensions Over Welfare Reforms
Andrew Cuomo Hints at Potential November Comeback Amid Democratic Primary Results
Curtis Sliwa Champions His Vision for New York City Amid Rising Crime Concerns
Federal Reserve Proposes Changes to Capital Rule Affecting Major Banks
EU TO HUNGARY: LET THEM PRIDE OR PREP FOR SHADE. ORBÁN TO EU: STAY IN YOUR LANE AND FIX YOUR OWN MESS.
Trump Escalates Criticism of Media Over Iran Strike Coverage
Trump Announces Upcoming US-Iran Meeting Amid Controversial Airstrikes
Trump Moves to Reshape Middle East Following Israel-Iran Conflict
Big Four Accounting Firms Fined in Exam Cheating Scandal
NATO Members Agree to 5% Defense Spending Target by 2035
Australia's Star Casino Secures $195 Million Rescue Package Amid Challenges
UK to Enhance Nuclear Capabilities with Acquisition of F-35A Fighter Jets
Russian Shadow Payments via Cryptocurrency Reach $9 Billion
Explosions Rock Doha as Iranian Missiles Target Qatar
“You Have 12 Hours to Flee”: Israeli Threat Campaign Targets Surviving Iranian Officials
Macron and Merz: Europe must arm itself in an unstable world
Germany and Italy Under Pressure to Repatriate $245bn of Gold from US Vaults
Airlines Evaluate Flight Cancellations Amid Escalating US-Iran Tensions
Starmer Invites Innovators to Join Government Talent Scheme
UK Economy’s Strong Opening Quarter Shows Signs of Cooling
Harrods Seeks Court Order to Secure Al Fayed Estate for Victims
BA and Singapore Airlines Cancel Dubai Flights Amid Middle East Tensions
Trump Faces Backlash from MAGA Base Over Iran Strikes
Meta Bets $14 B on Alexandr Wang to Drive AI Ambitions
WATCH: Israeli forces show the aftermath of a massive airstrike at Iran's Isfahan nuclear site
FedEx Founder Fred Smith, ‘Heart and Soul’ of the Company, Dies at 80
Chinese Factories Shift Away from U.S. Amid Trump‑Era Tariffs
Pimco Seizes Opportunity in Japan’s Dislocated Bond Market
×