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Is male fertility plummeting ?
It ’ s a conundrum dividing experts , one that ’ s screaming for more research on male reproductive health and its neglected role in human fertility
“ If you follow the curve from the 2017 sperm-decline meta-analysis , it predicts that by 2045 we will have a median sperm count of zero .”
In the dystopian novel The Handmaid ’ s Tale , author Margaret Atwood imagines an authoritarian society facing a devastating fertility crisis where few babies are born and women have been stripped of their rights to the point where those who are still fertile are forced to bear the children of powerful and prominent men , at least from those few still able to father offspring .
Beyond reaffirming today ’ s reality that women suffer the most from social attempts to engineer human reproduction , the book has popularised a growing anxiety over whether the human species will be able to reproduce itself in the future — a fear that isn ’ t just found in fiction but is also the conclusion of scientific research pointing to the dramatic drop in global male sperm counts over the last decades .
A review of medical studies first published in 2017 and then updated last year found that the number of sperms , or the male cells that combine with female eggs to produce offspring , have more than halved since 1973 in countries all around the world , from America and Europe to Africa and Asia . In light of the essential role played by sperm in human reproduction , some experts have sounded warning bells about a potential threat to humanity .
“ If you follow the curve from the 2017 spermdecline meta-analysis , it predicts that by 2045 we will have a median sperm count of zero ,” study author Dr Shanna Swann , a professor of environmental medicine and public health at the Mount Sinai School of Medicine , told the Guardian . “ It is speculative to extrapolate , but there is also no evidence that it is tapering off . This means that most couples may have to use assisted reproduction .”
But while fertility doctors can now help many couples conceive with assisted reproductive technology ( ART ), success rates are still low , meaning that the approach is nowhere near being able to replace natural conception . For instance , the US CDC reports that 330,773 ART cycles were performed in the US in 2019 , but these resulted in only 77,998 live births . Overall , roughly two percent of all babies are born through ART every year in the US .
Other researchers , however , caution that we shouldn ’ t jump to conclusions about plummeting sperm counts and their apocalyptic implications , pointing to several assumptions and variables that may be confounding the apparently alarming research findings .
“ We identify weaknesses and inconsistencies in the SCD �Sperm Count Decline hypothesis� , and propose an alternative framework to guide research on sperm count trends : the Sperm Count Biovariability hypothesis ( SCB ),” wrote a team of researchers in a 2021 critique of the review published in Human Fertility .
One of the paper ’ s lead authors , Marion Boulicault , told ��o�a� �ea�th �sia��aci�c that , though the 2017 meta-analysis was methodologically rigorous , its authors didn ’ t consider or test alternative explanations for the variation in sperm count numbers recorded over time .
“ Various semen analysis parameters , including sperm count , change in response to factors like the season , changes in diet , incidence with which men take a hot bath — so essentially there ’ s a whole range of other factors that could potentially play a role in explaining the drop in sperm count , and what we were noting is that potential alternative hypotheses weren ’ t fully acknowledged or explored in the meta-analysis ,” said Boulicault , who ’ s the Director of Interdisciplinary Research at the Harvard GenderSci Lab .
Another data point that should give pause to those concerned about a global fertility crisis is that sperm count concentration averages calculated in the meta-analysis are above 40 million per millimeter , surpassing the normal sperm count threshold that is usually a sign of healthy fertility .
“ They assume the 1970s ’ average sperm count concentration among men from so-called ‘ Western ’ countries constitutes the optimum concentration , and that today ’ s lower average concentrations are necessarily a sign of pathology . But they don ’ t consider alternative assumptions . Could it be that 1970s concentrations were potentially abnormally elevated ?” posits Boulicault . “ That may not be the case and the authors may very well be right that today ’ s sperm count concentrations are signs of a crisis for male health , but it ’ s irresponsible to make those claims without carefully acknowledging and considering alternatives , especially given their significance .”
Some sperm analysis experts are also sceptical about the alarming conclusion that humanity is at risk because there are different sperm counting methods that have changed over time , potentially leading to varying results that are hard to compare . “ Counting
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