We're headed for a sperm drought
Males are producing less sperm than they were 40 years ago.
Although the human race is far from extinction, sperm count in Western countries has declined steadily by up to a massive 60 percent over the last four decades.
Israeli scientists in the scientific journal Human Reproduction Update, looked at 7500 specimens from males all over the world.
They found a worrying trend that is continuing today. Not only does this trend signify an increase in male infertility, but also a warning about male health.
Professor Kate Loveland, Head of the Centre for Reproductive Health at Hudson Institute, is concerned about this trend.
"Our fertility provides a snapshot of our health," she says.
So, what's happened to our men over the last 40 years? Scientists agree that the trend is environmental and lifestyle related. Our changing diet, sedentary lifestyle and chemicals around us are to blame.
Men in western countries are larger than they were in the past. Obesity not only affects health, but fertility as well.
"It's very clear that that's a factor affecting the way our hormones and immune system functions," says Professor Loveland.
Sugary and fatty diets also take the blame.
"Sperm production is reduced, and sperm DNA damage is increased when we ingest these foods," she says.
Our love of plastic is also to blame
The lining of our coffee cups, pizza boxes and even the glasses resting on our nose all contain plastics that play havoc with our hormones.
Our hormones are controlled by the endocrine system. Endocrine disrupting chemicals are any chemical that affects our endocrine system. They could copy the hormone, stop the hormone or disrupt how it works.
Our fertility relies heavily on hormones and the endocrine system to work efficiently.
"The elephant in the room is the endocrine disruptor chemicals. They are surrounding us," says Professor Loveland.
During pregnancy, these chemicals can influence the size of the growing testis and ovaries in the womb, leading to fertility issues later in adult life.
Also, ibuprofen and paracetamol can affect male fertility in the womb when taken by the mother. It's important during pregnancy that the use of these medicines is minimised.
The effects can be passed down
These chemicals can affect generations of people.
"What our grandmother ate, can affect her grandchildren," says professor Loveland. "While our grandmother was pregnant with our mother, our mother was making the foundations of our generation's ovary or the testis (in her immature eggs) while she was growing as an embryo inside her mother."
Exposure to chemicals while pregnant is now seen as very important.
"It's very clear that the world has now passed through several generations of exposure to environmental chemicals.
It's important as a society to consider how we address that," says Professor Loveland.
Improving health and fertility
While you might not be able to change your grandmother's daily diet of chips with bacon and eggs, there are other ways our men can improve their reproductive health.
By maintaining a healthy body weight and eating plenty of fresh fruit and vegetables, men not only have the chance to improve their overall health, but their fertility too.
They can also improve their fertility by exercising and limiting their exposure to chemicals, both prescription medications and in the environment.