The first systematic review and meta-analysis of trends in sperm count is reporting a significant decline in sperm concentration and total sperm count among men from Western countries. The study, published in Human Reproduction Update , shows that the proportion of men with sperm counts below the threshold for subfertility or infertility is increasing.
Meta-regression analysis of 185 studies between 1973 and 2011 found a 52.4 per cent decline in sperm concentration, and a 59.3 per cent decline in total sperm count, among men from North America, Europe, Australia and New Zealand. In contrast, no significant decline was seen in South America, Asia and Africa, where far fewer studies have been conducted.
“Decreasing sperm count has been of great concern since it was first reported 25 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,” said co-author, Dr. Shanna H Swan, from Mount Sinai in New York.
Sperm count has previously been associated with environmental and lifestyle influences, including prenatal chemical exposure, adult pesticide exposure, smoking, stress and obesity.