Human sperm count has halved in the last 50 years. Do we need to be worried?
Is there a male fertility crisis in the world – or are we exaggerating it [1, 2]?
What’s the newest information on male fertility?
As reported in a study published in the journal Human Reproductive Update in 2022, sperm counts have declined by over 50 percent over the last 5 decades. [3].The global birth rate is also at a record low, with more than half of the world’s population living in countries where the fertility rate is below two children per woman [4].
In addition to low sperm count, BBC reports a decline in testosterone levels among men and an increase in testicular cancer and erectile dysfunction. A fundamental function of any species is reproduction, according to urologist Michael Eisenberg [5]. If there’s a sign that reproduction is declining, that’s a significant finding.
In general, infertility affects one out of every six people worldwide, according to a new report from the World Health Organization [6].
How come male fertility is dropping?
Some theories have emerged regarding the cause of the decline. BBC defines epigenetic changes as changes in the way genes work brought about by environmental or lifestyle factors.
Hagai Levine, an epidemiology professor, states that this declining sperm count might be a sign of poor health across generations. Furthermore, there is a strong link between a man’s reproductive health and overall health, which could lead to a general decline in health.
It could also be a sign that we may not be as healthy as we once were, Eisenberg said. Levine added that, in addition to stress, maternal smoking and exposure to manmade chemicals in plastic, such as phthalates, can also impede the development of male reproductive systems.
Climate change and the environment could also have an effect. According to a study from 2022, rising temperatures negatively affect sperm quality [7].
According to the study, heat stress is the most influential factor in reproductive function in mammals. Aside from that, BBC writes that “chemicals in plastics, household medications, food chains and air” can damage or break sperm DNA.
Is this a cause for concern?
Opinions on the matter are mixed, as The New York Times points out, “no one knows what an ‘optimal’ sperm count is [8].” Fertility requires 40 million sperm per milliliter of semen, and sperm counts above that are not necessarily more fertile.
As a surgeon and assistant professor at the University of Utah School of Medicine, Dr Alexander Pastuczak said that semen analysis has evolved over the years. It is better than before.
There have been improvements in standardization, but it is not perfect. Taking the same sample of semen and analyzing it now would result in two different answers.
According to Levine, we are facing a public health crisis that may not be reversible. Sperm quality and count may indicate a larger problem, he added.
Dr Scott Lundy, a urologist at the Cleveland Clinic, agrees. “While it’s not a cause for panic, because the counts are by and large still normal, on average.” There is a risk that they could become abnormal in the future, and we have to recognize that and study that further.
[1] https://www.bbc.com/future/article/20230327-how-pollution-is-causing-a-male-fertility-crisis
[2] https://www.smithsonianmag.com/smart-news/human-sperm-counts-declining-worldwide-study-finds-180981138/
[3] https://academic.oup.com/humupd/article/29/2/157/6824414?login=false
[4] https://www.bbc.com/future/article/20230327-how-pollution-is-causing-a-male-fertility-crisis
[5] https://www.cnn.com/2022/11/18/health/sperm-counts-decline-debate/index.html#:~:text=The%20study%20concluded%20that%20globally,2.64%25%20per%20year%20after%202020.
[6] https://www.cnn.com/2023/04/03/health/infertility-global-prevalence-who-report/index.html
[7] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9288403/
[8] https://www.nytimes.com/2021/06/04/health/sperm-fertility-reproduction-crisis.html
[9] https://theweek.com/health-and-science/1022191/why-is-male-fertility-declining
