December 5, 2012
Sperm Count, Quality In Men Lower Now Than Two Decades Ago
Lawrence LeBlond for redOrbit.com - Your Universe Online
Male fertility is one of the most controversial issues in medical science. Recent studies have shown that some chemicals can harm male fertility while others have shown foods that actually boost it. Despite all the science, it seems sperm counts in men are dropping all around the world. And no place seems more threatened by sperm loss than France.
The study, which covered more than 26,000 French men over a 17-year period, is important because it shows that while the results cannot be extrapolated to other countries, it does support other studies from elsewhere that have shown similar declines in semen concentration and quality in recent years.
“To our knowledge, this is the first study concluding a severe and general decrease in sperm concentration and morphology at the scale of a whole country over a substantial period,” said report coauthor, epidemiologist Dr Joelle Le Moal, an environmental health epidemiologist at the Institut de Veille Sanitaire, Saint Maurice, France. “This constitutes a serious public health warning.”
“This is the most important study carried out in France and probably in the world considering that you have a sample that's close to the general population,” Le Moal told AFP in an interview.
Dr Allan Pacey, senior lecturer in andrology at the University of Sheffield, pointed out that sperm count in the men–average age of 35–fell from 73.6 million to 49.9 million per milliliter. But according to the World Health Organization (WHO), this is still well within the fertile range, which it places at 15 million per milliliter.
For the study, the team used the assisted reproduction technology (ART) database Fivnat, which collected data from 126 main ART centers in France. The researchers examined semen samples provided by men who were the partners of women undergoing fertility treatment due to blocked or missing fallopian tubes and not for male fertility issues.
Le Moal said while the average values fall within the “fertile” range as set by the WHO, that´s all it is: an average. They found that some men in the study did fall below the 15 million/ml threshold, “below which sperm concentration is expected to influence the time it takes to conceive.”
The researchers also looked at how well the sperm moved (motility) and found that the proportion of motile sperm increased slightly from 49.5% to 53.6% between 1989 and 2005.
Although the team factored in variables that could have affected their results, such as age, time of the year, the center where the men gave samples, and technique used, they were unable to control for socioeconomic factors, including smoking and weight, which has been known to affect semen quality and concentration. Despite this, the authors say that most men in France who are involved in fertility treatments with their partners tended to be better educated, less likely to smoke and not overweight.
"Therefore, the real values for sperm parameters in the general population could be slightly lower than those that we present and the decreases could possibly be stronger," the researchers wrote.
The authors say more research is needed into what the possible causes of semen decline are. Some studies have already pointed to environmental factors such as endocrine disruptors (chemicals that disturb hormonal balance) that may play a role in semen decline. Also, such factors could be passed down through the generations, which can contribute to a longer process of decline in fertility.
Male fertility has seen much debate over the past 20 years in regards to decline in semen quality. The debate has been generally equal between both sides, with the latest research adding weight to the numerous European studies that suggest one in five men have a sperm count low enough to impair fertility.
“Something in our modern lifestyle, diet or environment like chemical exposure, is causing this,” said Professor Richard Sharpe, of University of Edinburgh. “We still do not know which are the most important factors, but perhaps the most likely is a combination, a double whammy of changes, such as a high-fat diet combined with increased environmental chemical exposures.”
Whatever the reasons for falling sperm count are, Le Moal told the Guardian´s Ian Sample: “it could be a problem for the next generation's health” because our reproductive cells are the beginning of all human development.
Jens Peter Bonde, a professor of occupational medicine at Copenhagen University hospital, said that Le Moal´s study shows results that are much different from other similar studies, and because of such, it demonstrates just how tricky sperm counting can be.
Le Moal´s study reported an average sperm count of 94.6 million/ml in 1989. But one of the largest French studies, reported in 1995, found that sperm counts had fallen from an average of 89 million/ml in 1973 to 60 million/ml in 1992. This study finding suggests either their results are extremely low or Le Moal´s are extraordinarily high.
“This conflicting data illustrates the problems with comparing sperm counting across centres without strict control of counting methods. Unfortunately, I don't think this new study helps much to settle the ongoing controversy," said Bonde.
Even though sharp contrasts are being observed in studies across the board, some noted that they all point to the same thing: sperm counts are falling.
The new study is a “big step towards resolving the falling sperm count issue,” said Sharpe. Since the men involved in the study were more likely to be representative of the general population, it “confirms that sperm counts have, or are, falling and essentially dispels [any] previous controversy´” he said.
“I simply do not accept that the basic methods for counting sperm have changed down the years, so there's no reason why sperm counts should go down unless it is real,” he added.
This issue of male semen quality is a much bigger issue today than it would have been 30 years ago, when women were having children at a younger age, according to Sharpe.
“Now, women are having their kids more in the 30-35 year range when their fertility is down by 40-50% compared with when in their 20s,” he explained. “This, combined with decreasing sperm counts in their male partner, leads to only one outcome: more couples are going to be experiencing fertility problems.”
This is all the more reason that research now needs to focus on why sperm counts are declining, such as dietary, environmental and lifestyle factors, according to Sharpe.
“Armed with such knowledge, we can potentially prevent or reverse the adverse changes in sperm counts. Without it, we have to expect that sperm counts will continue to decrease,” Sharpe added.
“Our public health warning may help health authorities to reinforce their actions on endocrine disruptors, hopefully at the European level, and to sustain research as well as monitoring systems. We plan to implement a national monitoring system with the French competent authority (the Biomedicine Agency), which now runs the national registry of ART. Our example could help other countries to implement their own systems. International monitoring systems could be a good idea to understand what is happening on human reproductive outcomes around the world, and evaluate public health actions in future," Le Moal concluded.