A new study has found that the sperm count of an average Frenchman fell by one-third between 1989 and 2005.
The findings of the report, published by the Human Reproduction journal on Wednesday, found that the number of sperm in one millilitre of the average 35-year-old French man's semen fell from about 74 million to about 50 million - a decrease of roughly 32 per cent.
"That's certainly within the normal range, but if you think about it, if there continues to be a decrease, we would expect
that we'll get into that infertile range," said Grace Centola, president of the Society for Male Reproduction and Urology in
The findings of the study are in line with similar research. One such study, two decades ago, found that global sperm rates fell by half in the years between 1940 and 1990.
"A decline in male reproduction endpoints has been suspected for several decades and is still debated all around the world," said Joelle Le Moal of the Institut de Veille Sanitaire in France, who led the study.
"Geographical differences have been observed between countries,and between areas inside countries."
Le Moal's team said global analyses have found decreases in sperm counts, as did recent studies in Israel, India, New Zealand and Tunisia.
Dr Allen Pacey, reproductive expert at the University of Sheffield, told Al Jazeera that "there is no evidence French men are becoming more infertile" than any other nation around the world.
Speaking to Al Jazeera, Pacey said 20 per cent of men around the world have lower sperm count than they should.
Finnish men, he said, "probably have the highest sperm counts of any men on the planet", while neighbouring Denmark has some of the lowest.
For the new study, Le Moal's team used a database of France's 126 fertility clinics that recorded men's semen samples
from 1989 through 2005.
They then narrowed their study to 26,600 samples provided by men whose female partners were later found to be infertile.
That, they say, minimises the risk the men had a fertility problem.
Over the 16-year period, the researchers found there was about a two per cent annual decrease in the number of sperm in one millilitre of the average man's semen.
"One would look at that and say it's not all that much. It isn't, but if it's occurring on a yearly basis it can add up,"
"Clearly if this type of decrease continues, we're going to find that we're going to have young men that have low
sperm counts," she said.
The World Health Organisation defines anything more than 15 million per millilitre of semen as normal.
However, the study's authors suggest that it may take longer for men with counts in the lower range of normal to conceive.
The researchers also found that there was an increase in the number of abnormally shaped sperm over the study period, which can also influence fertility.
Part of that finding, however, can be explained by scientists getting better at recognising misshapen swimmers, but
not all of it. "So both results are important," said Le Moal.