Sperm Count Dropping in Western World
The trend has occurred over 40 years
LONDON (Reuters) – Sperm counts in men from America, Europe, Australia and New Zealand have dropped by more than 50 percent in less than 40 years, researchers said on Tuesday.
They also said the rate of decline is not slowing. Both findings — in a meta-analysis bringing together various studies — pointed to a potential decline in male health and fertility.
“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.
“这项研究为全世界研究者和医疗主管机构敲了警钟，提醒他们探究精子数量持续急剧下降的原因”，Hagai Levine说道，他在耶路撒冷Hebrew大学Hadassah Braun公共健康和社区医疗学院共同领导了本次研究。
The analysis did not explore reasons for the decline, but researchers said falling sperm counts have previously been linked to various factors such as exposure to certain chemicals and pesticides, smoking, stress and obesity.
This suggests measures of sperm quality may reflect the impact of modern living on male health and act as a “canary in the coal mine” signaling broader health risks, they said.
Studies have reported declines in sperm count since the early 1990s, but many of those have been questioned because they did not account for potentially major confounding factors such as age, sexual activity and the types of men involved.
Working with a team of researchers in the United States, Brazil, Denmark, Israel and Spain, 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.
The results, published in the journal Human Reproduction Update, showed a 52.4 percent decline in sperm concentration and a 59.3 percent decline in total sperm count among North American, European, Australian and New Zealand men. The former measures the concentration of semen in a man’s ejaculation, while the latter is semen concentration multiplied by volume.
研究结果发表在《人类生育力调查》（Human Reproduction Update）期刊上，显示北美，欧洲，澳大利亚和新西兰男性精子浓度下降了52.4％，而精子总数下降了59.3％。前者测量的是男性一次射精量的精子浓度，而后者则是精子浓度乘以体积。
In contrast, no significant decline was seen in South America, Asia and Africa. The researchers noted, however, that far fewer studies have been conducted in these regions.
Experts asked to comment on the work said it was a comprehensive and well-conducted analysis and did a good job of adjusting for confounders that could have skewed its findings.
Daniel Brison, a specialist in embryology and stem cell biology at Britain’s Manchester University, said the findings had “major implications not just for fertility but for male health and wider public health”.
“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.”
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