There might be a lot of fish in the sea, but there are fewer little swimmers to go around, at least according to researchers studying male sperm.
A meta-analysis of previous studies, published in the journal Human Reproduction Update, showed that there has been a 59 percent decline in total sperm count — from 337.5 million in 1973 to 137.5 million over a 40 year span that ended in 2011. There was also a 52 percent decline in sperm concentration — from 99 million sperm per milliliter to about 47 million per milliliter, according to the data.
That’s a problem, according to scientists studying male reproduction.
"The extent of the decline is a heartache," lead researcher Dr. Hagai Levine of Hebrew University of Jerusalem told CNN. "It's hard to believe — it's hard to believe for me."
Low sperm count affects male fertility
The reason for the researchers’ concern: The number of men in Western countries like the United States, New Zealand and Australia with sperm concentrations below 40 million/ml is high, meaning that the number of little swimmers they produce is closer to the bottom of the acceptable range than the top. Normal sperm concentrations fall in a range from 15 million/ml to 200 million/ml, according to the Mayo Clinic.
A lower number may mean men will have a harder time fathering children.
Why men shouldn’t panic about low sperm count frequency yet
For the analysis, researchers looked at data from 43,000 men obtained in 185 studies conducted between 1973 and 2011. They then split the data into two groups: one with men from western countries and the other of men from other countries in South America, Asia and Africa. The western men saw the drop, but men from the “other” countries didn’t experience a significant change in sperm count.
Does this mean that birth rates in western countries are going to drop? Not necessarily. A meta-analysis is basically a round-up of information found in previous scientific research. The data isn’t always consistent and wasn’t always collected for the same reason or the same methods, so there’s no way to ensure the conclusions are absolutely accurate.
And the results of this study contradicted a controlled study of Danish men between 1996 and 2010 that showed no decline in sperm counts.
Regardless, Richard Sharpe, an expert in male reproductive health and professor at the University of Edinburgh, told The Guardian that this meta-analysis “is about as close as we are going to get” to being sure of a decline in male sperm counts.
Causes of low sperm count
But knowing the true cause of the drop is unlikely anytime soon, he said.
“That is primarily because we have seriously under-invested in male reproductive research.”
On an individual level, there is no one reason why sperm counts go down; it can be attributed to a variety of factors, ranging from lifestyle to environmental. Obesity, excessive tobacco, alcohol and drug use — and even working in jobs with prolonged sitting, like truck driving, can affect sperm counts. These can be managed through choices, but other causes of low sperm counts, including hormonal imbalances, conditions like Celiac’s disease and chromosomal deficiencies can’t always be readily fixed.
Seeing your doctor is the best way to learn more about your personal sperm count, according to the Mayo Clinic. Your doctor can analyze your semen levels and make recommendations for treatment if it’s needed.