July 25 (UPI) -- Researchers from Hebrew University have found that sperm concentration and total sperm count has significantly and steadily declined in Western men.
The study, published July 25 in Human Reproduction Update, was conducted by Hebrew University-Hadassah Braun School of Public Health and Community Medicine and the Icahn School of Medicine at Mount Sinai.
Researchers reviewed 7,500 studies and conducted meta-regression analysis on 185 studies between 1973 and 2011 to find a 52.4 percent decline in sperm concentration and a 59.3 percent decline in total sperm count in men from North America, Europe, Australia and New Zealand.
Researchers did not see a significant decline in sperm count in men from South America, Asia and Africa.
"Given the importance of sperm counts for male fertility and human health, 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, with the goal of prevention," Dr. Hagai Levine, head of the Environmental Health Track at the Hebrew University-Hadassah Braun School of Public Health and Community Medicine, said in a press release.
Researchers said the data demonstrates the proportion of men with sperm counts below the threshold for subfertility or infertility is increasing, and findings from other studies suggest that reduced sperm count is related to increased morbidity and mortality.
"Decreasing sperm count has been of great concern since it was first reported twenty-five years ago. This definitive study shows, for the first time, that this decline is strong and continuing. The fact that the decline is seen in Western countries strongly suggests that chemicals in commerce are playing a causal role in this trend," Dr. Shanna H Swan, a professor in the Department of Environmental Medicine and Public Health at the Icahn School of Medicine at Mount Sinai, said.
The study did not delve into the causes of decreased sperm count, but previous research has shown a link between decreasing sperm count and environmental and lifestyle factors.