Are men becoming less fertile? A new study suggests that sperm counts and concentrations have declined significantly among men from North America, Europe, Australia and New Zealand in the past four decades. The study, published in the journal Human Reproduction Update, is the largest and most comprehensive meta-analysis of sperm count data to date. It analyzed 185 studies involving nearly 43,000 men from 50 countries between 1973 and 2011.
The results are alarming: the researchers found a 52.4% decline in sperm concentration and a 59.3% decline in total sperm count among men from these regions over the study period. The decline was not observed in men from South America, Asia and Africa, but the researchers noted that there were fewer studies from these regions and the data quality was lower.
The researchers suggested that the decline in sperm count and concentration may have serious implications for male health and reproductive potential, as well as for the future of human population. They also called for urgent research on the causes and prevention of this phenomenon, and mentioned some possible factors that may contribute to the decline, such as exposure to environmental chemicals, lifestyle changes, obesity, stress and smoking.
“This 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 Dr. Hagai Levine, the lead author of the study and an epidemiologist at the Hebrew University of Jerusalem.
“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,” said Dr. Shanna Swan, a co-author of the study and a professor of environmental medicine and public health at the Icahn School of Medicine at Mount Sinai in New York.
“Sperm count is not just a measure of fertility but also a marker of general health. It is important to understand what is causing this decline as it may have serious implications for public health,” said Dr. Richard Sharpe, a professor at Edinburgh University who was not involved in the study.
The study has sparked a global debate over male fertility and its possible causes. Some experts have questioned the validity of the meta-analysis, arguing that it may have overlooked some factors that could affect sperm quality, such as age, ethnicity, seasonality and laboratory methods. Others have pointed out that sperm count is not the only determinant of male fertility, and that other aspects of sperm function, such as motility and morphology, should also be considered.
However, many experts have agreed that the study is a wake-up call for more research and action on male reproductive health. They have also urged men to take steps to improve their sperm quality, such as avoiding smoking, alcohol and drugs, maintaining a healthy weight and diet, exercising regularly and reducing stress.
“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 Dr. Swan. She added that men should avoid exposure to pesticides, plastics and other endocrine-disrupting chemicals that may interfere with hormone production and function.
The study also raises questions about the future of human reproduction and population growth. According to the United Nations, the world population is expected to reach 9.8 billion by 2050, with most of the growth occurring in Africa and Asia. However, if the decline in sperm count continues at the current rate, some experts warn that it could lead to a fertility crisis in some regions.
“We may be on the cusp of a scenario where infertility becomes endemic,” said Dr. Chris Barratt, a professor of reproductive medicine at Dundee University who was not involved in the study.
He added that while assisted reproductive technologies such as IVF could help some couples conceive, they are not a solution for everyone. “IVF cannot solve this problem; we need to find out why this is happening,” he said.
– Sweeping study shows sharply declining male fertility, Israel21c, July 26, 2017
– Sperm counts may be declining globally, review finds, adding to debate over male fertility, CNN, November 18, 2022
– Sperm counts drop globally: What’s impact on fertility, men’s health?, USA Today, November 15, 2022
– Male infertility: What you should know about sperm count and quality, The Conversation, November 12, 2022