A drop of more than 50 percent in less than 40 years have been noticed in sperm counts in men from America, Europe, Australia and New Zealand, researchers said recently.
And what is more alarming is that there is no letup in the rate of decline in sperm count. A potential decline in male health and fertility was pointed out by both the findings — in a meta-analysis bringing together various studies.
“This study is an urgent wake-up call for researchers and health authorities around the world to investigate the causes of the sharp ongoing drop in sperm count,” said Hagai Levine, who co-led the work at the Hebrew University-Hadassah Braun School of Public Health and Community Medicine in Jerusalem.
Falling sperm counts have previously been linked to various factors such as exposure to certain chemicals and pesticides, smoking, stress and obesity, researchers have said earlier even though the analysis did not explore reasons for the decline.
This suggests measures of sperm quality may act as a “canary in the coal mine” signalling broader health risks and may reflect the impact of modern living on male health, they said.
Due to factors such as not accounting for potentially major confounding factors such as age, sexual activity and the types of men involved, many of the studies and reports in declining sperm count have been questions even though such studies have been undertaken reporting declines in sperm count since the early 1990s.
Levine screened and brought together the findings of 185 sperm count studies from 1973 to 2011 and then conducted a so-called meta-regression analysis, working with a team of researchers in the United States, Brazil, Denmark, Israel and Spain.
A 59.3 percent decline in total sperm count and a 52.4 percent decline in sperm concentration among North American, European, Australian and New Zealand men was shown in the results which was published in the journal Human Reproduction Update.
While the former is semen concentration multiplied by volume, the later measures the concentration of semen in a man’s ejaculation.
In contrast, in South America, Asia and Africa, no significant decline was seen. However, far fewer studies have been conducted in these regions the researches noted.
The study did a good job of adjusting for confounders that could have skewed its findings and was a comprehensive and well-conducted analysis, said experts when asked to comment on the work.
The findings had “major implications not just for fertility but for male health and wider public health”, said Daniel Brison, a specialist in embryology and stem cell biology at Britain’s Manchester University.
“An unanswered question is whether the impact of whatever is causing declining sperm counts will be seen in future generations of children via epigenetic (gene modifications) or other mechanisms operating in sperm,” he said in an emailed comment.
Richard Sharpe at Edinburgh University added: “Given that we still do not know what lifestyle, dietary or chemical exposures might have caused this decrease, research efforts to identify (them) need to be redoubled and to be non-presumptive as to cause.”
(Adapted from CNBC)