Why is male fertility declining? Experts weigh in

Male fertility decline has become one of the most important and unsettling questions in reproductive medicine. There appears to have been a clear decline in sperm quality over the past 50 years, but the difficult truth is that there is no single, settled explanation.

That was one of the central messages delivered by United States researcher Dr Michael Eisenberg at the Fertility Society of Australia and New Zealand annual scientific meeting in Canberra. He examined a range of possible contributors to declining male fertility, from obesity and heat to mobile phones, chemicals and plastics.

The answer, at this stage, is not a neat one. There may be several causes working together. What is clear is that male reproductive health deserves serious attention, proper research and practical medical care rather than simplistic political explanations.

The Question of Declining Sperm Quality

There has been substantial concern about declining sperm quality in recent decades. Some earlier research suggested that the trend may have begun during the twentieth century, although the reliability of parts of that older research has been questioned.

Dr Eisenberg’s focus was on the stronger apparent trend over the last half century. Sperm quality has fallen, and researchers are trying to identify why.

It is tempting to seize on one explanation. A former senator recently suggested that male fertility was declining because society had become “woke”. That may make for an eye-catching comment, but it does not assist anyone trying to understand a genuine health issue. Fertility is complicated. Human biology, environment, lifestyle and modern living may all be relevant.

The responsible answer is that researchers do not yet know precisely which factor, or combination of factors, is responsible. But several plausible areas warrant careful investigation.

Possible Causes of Male Fertility Decline

1. Obesity and Physical Health

One possible contributor is obesity. People are generally more obese now than they were 50 or 60 years ago, and poor physical health can affect many bodily systems, including reproductive health.

Men who are unfit or obese may be more likely to have poorer sperm quality. This does not mean that every man with a higher weight will experience fertility difficulties, nor that fertility issues can simply be blamed on body size. It does mean that overall health matters.

For men concerned about fertility, attention to fitness, diet and general wellbeing is sensible. These issues should be addressed with a doctor, particularly where pregnancy has not occurred after a reasonable period of trying or where there are known reproductive concerns.

2. Radio Waves, Mobile Phones and Wi-Fi

Modern life involves constant exposure to electronic devices. Mobile phones, wireless networks and other sources of radiofrequency exposure are now ordinary features of work, travel and home life.

Dr Eisenberg identified radio waves as a possible area of inquiry. Mobile phones are often carried in a trouser pocket, close to the testicles. Given that the testicles are reproductive organs sensitive to external influences, it is reasonable to ask whether this type of exposure could affect sperm production or sperm quality.

That question remains unresolved. It should not be presented as established fact that a phone in a pocket causes infertility. Equally, it should not be dismissed without ongoing research. Fertility medicine must be led by evidence, not assumptions.

3. Rising Temperatures and Heat Exposure

Heat is another possible factor. The Earth is warming, and testicular function is sensitive to temperature. It follows that higher environmental temperatures may have some influence on sperm production.

This is an area where the larger environmental question and personal reproductive health may intersect. The precise extent of any effect is still being explored, but it is another plausible piece of a much larger puzzle.

4. Chemicals, Plastics and Nanoplastics

Perhaps the most confronting area of research concerns chemicals and plastics. Plastics are everywhere in contemporary life. They are difficult to avoid entirely, appearing in food packaging, household goods, workplaces and consumer products.

Researchers are examining whether exposure to chemicals and plastics might contribute to reproductive changes. Of particular concern is the emerging study of nanoplastics, extremely small plastic particles that may enter the body.

Studies have identified plastic particles in men’s testicles. Research has also compared nanoplastics found in human testicles with those found in dogs’ testicles. That is a striking and deeply concerning subject for further investigation.

No responsible practitioner should jump from early findings to definitive conclusions. However, this research highlights why environmental exposure must remain on the agenda in fertility medicine. The question is not merely whether one substance is responsible, but whether a lifetime of combined exposures may affect reproductive health.

There May Be More Than One Cause

The key point from Dr Eisenberg’s presentation was refreshingly honest: we do not yet know.

Obesity, heat, electronic devices, chemicals and plastics may each play a role. Some may have little effect on their own but become more significant in combination with other factors. There may also be influences not yet identified.

That uncertainty is not a reason for inaction. It is a reason for better research and thoughtful clinical practice. Where doctors can identify lifestyle factors or exposures that may be relevant for a particular patient, they can help reduce risks and support the best possible reproductive outcomes.

People considering fertility treatment or concerned about reproductive options should obtain advice tailored to their circumstances. Page Provan’s fertility lawyers assist intended parents with the legal issues that can arise alongside IVF, donor conception and surrogacy arrangements.

Embryo Law in Italy: When Law Overrides Science

The scientific meeting also raised a starkly different fertility issue: the consequences of laws that treat embryos as legal persons.

Associate Professor Laura Rienzi from Italy discussed research into how long embryos may remain frozen before being used. Italy has become a notable place for this research because Italian law, for religious reasons, has treated embryos as people.

The consequence is extraordinary. Embryos cannot simply be discarded, even where they are defective or have been stored for a very long time. They must remain in storage.

Embryos are tiny, often smaller than the ball of a pen, and are stored in liquid nitrogen. Treating every embryo as a person with human rights creates profound practical and ethical difficulties. It also has the potential to displace sound scientific and medical judgment.

The effect of religiously driven law was once even more concerning. Italian rules required doctors to transfer three embryos at a time. That approach placed women and babies at greater risk because multiple pregnancies carry additional medical complications.

Thankfully, Italy’s Supreme Court intervened and struck down that requirement. Doctors were then able to make decisions based on scientific practice rather than a rigid legal rule.

Why Single Embryo Transfer Matters

Australia and New Zealand have been world leaders in single embryo transfer. Rather than transferring multiple embryos in the hope that one will implant, the focus is on transferring one embryo at a time where clinically appropriate.

This approach significantly reduces the risk of multiple pregnancy. That matters for the woman carrying the pregnancy and for the children born as a result.

Single embryo transfer demonstrates what fertility care should look like: decisions guided by medical evidence, patient safety and the welfare of children. The legal framework should support that work, not force doctors into practices that increase avoidable risk.

For broader national context, the Australian Government’s information on IVF and assisted reproductive technology outlines the role that assisted reproduction plays for people seeking to build their families.

Fertility Law Must Keep Pace With Fertility Science

Fertility science moves quickly. Research into sperm quality, environmental exposure, embryo development and assisted reproductive technology continues to evolve. Laws and ethical frameworks need to be capable of responding to that science with care and common sense.

That is particularly important in surrogacy and donor conception, where intended parents can face legal questions well before a child is born. Clear advice at the outset can help families understand their responsibilities, protect all parties and prepare for the legal steps ahead.

Those seeking assistance with an Australian surrogacy arrangement can obtain guidance from experienced surrogacy lawyers, particularly before entering into arrangements, beginning treatment or making decisions about embryos and donation.

Looking Ahead

The next major Fertility Society gathering will form part of the International Federation of Fertility Societies World Congress in Brisbane next April. It promises to be a substantial event, bringing together professionals working across reproductive medicine, embryology, research, law and fertility care.

These conferences matter because fertility is never just a medical issue or just a legal issue. It is deeply personal, often emotional and increasingly shaped by scientific developments that would have been unimaginable a generation ago.

As research continues into male fertility decline, the most useful position is neither panic nor complacency. It is curiosity, evidence, careful medical advice and a willingness to confront difficult questions honestly.

About Stephen Page

Stephen Page is widely regarded as one of Australia’s leading surrogacy lawyers and is a recognised authority in fertility and family law. Through Page Provan Family and Fertility Lawyers, he has assisted thousands of intended parents and families navigating surrogacy, donor arrangements and assisted reproduction across Australia and internationally. For confidential advice about a fertility law matter, contact Page Provan.