It's the first large scale review of sperm count and quality ever to produce results like these - and scientists are 'shocked.'

The study discovered that sperm count in males from Western countries (North America, Europe and Australia) has declined by 50 percent in less than 40 years.

Now they're saying it's a wake-up call that could indicate a looming health crisis on the horizon for Western countries.  

"Given the importance of sperm counts for male fertility and human health, this study is an urgent wake-up call for researchers and health authorities around the world..."" said Hagai Levine, one of the researchers from the Hebrew University of Jerusalem.

Sperm count is the best method we have to determine male fertility, it measures the concentration of sperm in a man's ejaculate.

Since 1992, studies have been pointing to declining sperm count in Western men.

But it wasn't until more recently that we got the full, frightening picture of what was actually going on.

A team of scientists analyzed the sperm count data collected from nearly 43,000 men between 1973 and 2001. What they found was seriously worrying:

In Western studies of sperm count, there was a 52.4 percent decline in sperm concentration and a 59.3 percent decline in total sperm count between 1973 and 2011.

Does this mean that humanity is on the road to a fertility disaster that could possibly even lead to our extinction?

Find out what the experts have to say on the next page.

After comparing their findings with more recent studies of a similar nature, the team realized that there was no sign that a decline in sperm count would level-off.

While scientists still don't know what's causing Western men's sperm count to drop, they suspect it could be an exposure to chemicals that have a part in it.

Some suggest that a mother's exposure to certain chemicals could alter the reproductive tract of a baby boy; however, other theories suggest that the global obesity epidemic and stress could be responsible for the cut in sperm counts.

"Since we don't know what could be causing it, it's worrisome," says Peter Schlegel, chairman of urology at Weill Cornell Medicine in New York.

What about the rest of the world? There wasn't enough data from non-Western countries to say for sure whether sperm counts are falling there too.

While we don't need to panic yet, researchers are taking note of these troubling findings.

More studies will have to be done to find out exactly why such a dramatic decrease in sperm count is happening among Western men.

In the meantime, boys, eat your vegetables!

[h/t Science Alert / NPR/ Science of Us]