London - Modern life is feared to be damaging men’s fertility after a study found the average sperm count has fallen almost 60 percent in a generation.
Scientists said the decline in sperm quality should be a "wake-up call" and warned that, coupled with women increasingly having children later, it provides a "double whammy" of fertility problems for couples trying for a baby.
The decline in male fertility was only seen in Western countries, suggesting lifestyle and environmental factors are to blame. Obesity, stress, pesticides and chemicals found in our homes are all thought to hamper sperm production.
A review of 185 studies found the average sperm count of a man from Europe, North America, Australia and New Zealand has fallen by 59.3 percent between 1973 and 2011, with a steeper decline since 1995.
But no significant decline was seen in men from South America, Asia and Africa, although there were fewer studies in these areas.
Dr Hagai Levine, of the Hebrew University of Jerusalem, who led the research, said: "Given the importance of sperm counts for male fertility and health, this study is an urgent wake-up call for researchers and health authorities to investigate the causes of the sharp ongoing drop in sperm count, with the goal of prevention.
"Previous studies have associated low sperm count with environmental and lifestyle influences including pre-natal chemical exposure, adult pesticide exposure, smoking, stress and obesity."
Co-author Professor Shanna Swan, from the Icahn School of Medicine in New York, said: "The fact that the decline is seen in Western countries strongly suggests that chemicals in commerce are playing a causal role in this trend."
Many plastics contain chemicals thought to block enzymes that are important for testosterone production, such as bisphenol A, which is found in baby bottles, plastic plates and the linings of food and drink cans.
Responding to the findings, which were published in the journal Human Reproduction Update, Professor Richard Sharpe, from the MRC Centre for Reproductive Health at Edinburgh University, said: "Across Northern Europe today, more than 15 percent of young men have a sperm count low enough to impair their fertility and, as the study indicates, this is likely to get worse rather than better.
"What is not so widely appreciated is that the coincidence of this change in men with delay in couples trying for a baby until the female partner is in her 30s, when her fertility is declining, creates a double whammy for couple fertility in modern Western societies."
But Allan Pacey, professor of andrology at Sheffield University, said: "The debate has not yet been resolved and there is clearly much work still to be done."
HOW SPERM IS AFFECTED
Obesity may reduce sperm production or alter the structure of sperm. Two in three British men are overweight or obese
Chemicals found in everyday plastics, such as one called bisphenol A, are thought to block enzymes important for testosterone production while men are still babies inside the womb
Exposure to pesticides as adults is also thought to affect how enzymes work in the body
Stress hormones called glucocorticoids may trigger receptors in the testes, leading to less sperm being made
© Daily Mail