Australian men’s sperm counts are dropping dramatically but researchers believe the solution may be as simple as improving lifestyle.

Data shows since 1973 sperm counts have halved, dropping by 1.4 per cent a year and showing no sign of levelling out.

It has not yet reached a point of concern but, if the trend continues, in another century or so we may be facing a fertility crisis.

But it can be stopped by addressing lifestyle issues such as diet and exercise, experts say. A comprehensive check of data from multiple studies for the European Society of Human Reproduction and Embryology found “a significant decline in sperm counts between 1973 and 2011 driven by a 50-60 per cent decline among men from North America, Europe, Australia and New Zealand”.

“Because of the significant public health implications of these results, research on the causes of this continuing decline is urgently needed,” the researchers state.

The count in men in Western societies fell from 99 million sperm per millilitre of ejaculate to 47.1 million per millilitre over 1973-2011, still well above the 15 million per millilitre mark which would cause alarm over fertility.

Normal sperm densities range from 15 million to greater than 200 million sperm per millilitre of semen.

The issue was not seen in men from Africa, Asia and South America, but the authors say there have been limited studies in these regions.

Separate research also shows a good sperm count appears to be a predictor of future health — men who had high sperm counts were, on average, hospitalised seven years later than men with a low sperm count.

The Danish study points to semen as a “universal biomarker for future health, not explained by lifestyle or socio-economic status”.

Dr Nicole McPherson, who runs the Sperm and Embryo Biology Research Group at the Robinson Research Institute and the Freemasons Foundation Centre for Men’s Health at the University of Adelaide, said sperm has emerged as the “canary in the coalmine”.

“It appears to be an early warning predictor of other health problems from heart disease to diabetes,” she said.

“This comes as we have seen a decline in sperm rates among Western societies — the bottom line is the sperm count is going down.

“While no-one can prove exactly why, it may be to do with the Western lifestyle — high sugar diet, sedentary lifestyle, lack of exercise and so on. There is not a lot of evidence but we can speculate that a healthy diet and getting more exercise are likely going to improve things — everything is linked.”

Other factors include smoking, illicit drugs, alcohol, pesticides, chemicals, and even office work and tight underpants. Semen is produced at 35.5C while the body temperature is about 37C and if the scrotum is heated by things like prolonged sitting or continued wearing of tight pants, it can have an effect on production.

The Advertiser is running a series of men’s health advice blogs with experts in urology, fertility, psychology, cardiology and sexual health. Leave your questions in the comments box below — we’re talking sperm at 12.30pm Thursday.