Home' Trinidad and Tobago Guardian : August 8th 2017 Contents A22 body & soul
guardian.co.tt Tuesday, August 8, 2017
Sperm counts in Western countries have de-
creased by half in recent years, suggesting a con-
tinuing and significant decline in male repro-
ductive health, a new evidence review reports.
Sperm concentration decreased an average 52 per
cent between 1973 and 2011, while total sperm count
declined by 59 per cent during that period, researchers
concluded after combining data from 185 studies. The
research involved nearly 43,000 men in all.
"We found that sperm counts and concentrations
have declined significantly and are continuing to de-
cline in men from Western countries," said senior
researcher Shanna Swan.
"We don't have a lot of data in men from non-West-
ern countries, so we can't draw conclusions about
that part of the world," added Swan, a professor of
environmental medicine at the Icahn School of Med-
icine at Mount Sinai in New York City.
But in Europe, North America, New Zealand and
Australia, "the declines are strong, significant and
continuing," she said.
The new findings come on the 25th anniversary of
the first study to observe a decline in sperm counts,
Swan said. The original study, published in 1992,
found that sperm counts had declined 50 per cent
over 50 years.
The continued decline raises concerns about male
fertility, and also male health in general, Swan said.
"We are worried about these low sperm counts not
only because people have trouble conceiving, but also
because men with low sperm counts go on to have
higher all-cause mortality," Swan said. Studies have
shown "they die younger and they have more disease,
particularly cardiovascular disease and cancer," she
"It really makes the implications of our study much
greater," she continued. "We're not talking about
making babies. We're also talking about survival
No one knows why sperm counts continue to de-
cline, but researchers believe it's likely due to factors
associated with a modern lifestyle, Swan said. These
factors include exposure to man-made chemicals,
increased levels of stress, widespread obesity, poor
nutrition, lack of physical exercise and smoking.
These factors can temporarily reduce a man's fertili-
ty, but researchers think the real damage is being done
during exposures occurring in the womb, Swan said.
"Research has found that when a mother smokes,
her son has a lower sperm count, regardless of his
own smoking," Swan said. "That says what a man
is exposed to when he's in utero is important. The
mother's exposure will cause a change that stays with
the man his entire life."
Experts are divided on whether the decline in sperm
counts will have any impact on male fertility in the
Modern men still have 66.4 million sperm per
milliliter of semen, compared with 92.8 million per
milliliter from men nearly four decades ago, said Dr
Avner Hershlag, chief of Northwell Health Fertility
in Manhasset, NY.
"It's not all in the numbers," Hershlag said. "It is
estimated about 20 per cent of men who have achieved
a pregnancy with their partners without treatment
have abnormal sperm. There is no proof that parallel
to the decline in numbers there has been a decline in
the true ability of males to impregnate their partners."
Furthermore, he said, "every person you know is
the product of one egg and one sperm, so why do
we need millions of sperm knocking on the wall of
a single egg?"
However, if the trend continues, it could have an
impact, said Dr Peter Schlegel, a professor of repro-
ductive medicine and urologist-in-chief for New
York-Presbyterian/Weill Cornell Medical Center
in New York City.
The study appears in the July 25 issue of the journal
Human Reproduction Update.
Sperm counts decline
in Western nations
Sperm counts in Western countries have decreased by half in recent years.
(SOURCES: Shanna Swan, PhD, professor,
environmental medicine, Icahn School of Medicine
at Mount Sinai, New York City; Avner Hershlag, MD,
chief, Northwell Health Fertility, Manhasset, N.; Peter
Schlegel, MD, professor, reproductive medicine, and
urologist-in-chief, New York-Presbyterian/Weill Cornell
Medical Center, New York City; Human Reproduction
Update, July 25, 2017)
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