Declining Sperm Count in Western Men Does Not Necessarily Mean a Decline in Fertility

Sperm

Sperm

Recent studies have shown that sperm counts in men are declining, especially in Western countries, leading to apocalyptic predictions about the possible extinction of the human species. But Harvard researchers have analyzed these claims by re-evaluating the evidence presented in a famous 2017 meta-analysis.

In 2017, the journal Human Reproduction Update had published a meta-analysis on the average sperm concentration in men in Western countries, the most rigorous yet. According to this study, sperm counts dropped by 59.3% between 1973 and 2011, and there is no sign of this stopping. The so-called Western populations include North America, Europe, Australia, and New Zealand. In contrast, populations in South America, Asia, and Africa did not experience a statistically significant decrease in sperm count.

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Nevertheless, the study in question has entered the public debate and been used to support political narratives claiming that the fertility of white men from Western countries is at risk. In a new study from the Harvard GenderSci Lab, published in the journal Human Fertility, Marion Boulicault, Sarah Richardson, and their colleagues propose an alternative hypothesis after re-evaluating previous claims.

Weaknesses of the declining sperm count hypothesis

Among many other criticisms, the Harvard GenderSci Lab study notes that there is no conceptual justification for comparing the average sperm count of Western men in the 1970s with that in 2013. This is because it implies that the sperm count of Western men in the 1970s represents an optimum, and thus assumes that the body and environment of Western men in that period are natural or even exemplary.

Moreover, a decline in sperm count does not predict a decline in the fertility of men. In fact, the meta-analysis reports a decline from 99 million sperm cells per milliliter in 1970 to 47.1 million in 2013, but according to the World Health Organization (WHO), the so-called “normal” range is between 15 and 259 million sperm cells per milliliter.

Because male infertility is a complex biological and social phenomenon, it cannot be measured by the single measure of sperm count. Although azoospermia – the complete absence of sperm in the semen – guarantees infertility, researchers have found that some men with low sperm counts can still conceive, while others with higher sperm counts cannot. Taking into account, for example, sperm motility or morphology could have added an additional qualitative dimension to the analysis.

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Misuse of the 2017 study

The Harvard GenderSci Lab specializes, among other things, in the analysis of bias and media treatment of scientific issues about sex, gender, and reproduction. As such, they are interested in media coverage of male infertility and have noticed that some political groups are using Levine and Swan’s meta-analysis for ideological purposes, particularly the discourse of the American Alt-Right, White Supremacy, and the men’s rights movement.

In their discourse analyses, Western men are portrayed as “vulnerable and threatened by forces beyond their control, and as victims of a liberal-feminist environment.” Some right-wing conspiracy theorists have tried to link the declining sperm count to the erosion of social status and the feminization of the Western male, and have even gone so far as to use the term Soy Boys to describe men who are deficient in testosterone.

These claims not only distort what contributes to the reproductive health of men in contemporary societies but also obscure the fertility problems of men in East Asia, the Middle East, or the South, as well as the environmental damage to reproduction, such as the effects of endocrine disruptors.

A new approach

The Harvard GenderSci Lab study suggests the following alternative: “Sperm count varies over a wide range, much of which can be considered non-pathological and typical of the human species, and that above a critical threshold, more sperm is not necessarily an indicator of better health or higher fertility risk. ”

The authors call this the sperm count variability hypothesis. This approach, they say, would provide a more critical understanding of the factors that influence reproductive health in all men.

Read Also: Drinking Alcohol is Never Safe During Pregnancy According To Study

References

The future of sperm: a biovariability framework for understanding global sperm count trends

Temporal trends in sperm count: a systematic review and meta-regression analysis

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