In a recently published book, scientific duo Shanna H. Swan and Stacey Colino show that the number of sperm produced in Western countries fell 59% between 1973 and 2011. If the current trajectory continues, that number could reach zero. from 2045.
Will the pandemic bring down the fertility rate? According to INSEE (National Institute for Statistics and Economic Studies), in any case, the number of births registered in France in January fell by 13% compared to January 2020. An unprecedented drop since 1975, in a context " of health crisis and high uncertainty, [which] may have discouraged couples from procreating or encourage them to postpone their parenting plans for several months, " according to the Institute for Statistical Studies. Admittedly, the number of births in France has been falling steadily for six years, but INSEE notes that the fall observed in January is "out of proportion to the declines that have been observed in the past ".
Widespread assisted reproduction in 2045?
A trend that remains to be confirmed, therefore… and to which another even more global phenomenon could be added. That of the presence, in our organism, of certain chemical substances with harmful effects on fertility. This is what the scientific duo Shanna H. Swan and Stacey Colino highlight in a new book recently published in English, Count Down - How Our Modern World Is Threatening Sperm Counts, Altering Male and Female Reproductive Development, and Imperiling the Future of the Human Race (Simon & Schuster editions, 2021).
In an interview with the British daily The Guardian , Shanna H. Swan, also a professor at the Mount Sinai medical school in New York, goes so far as to reiterate fears she had already expressed a few years ago , stating that " most couples could have assisted reproduction in 2045 ".
Extract from the book cover © Simon & Schuster
In a study she co-signed in 2017 , Swan indeed showed that the number of sperm produced in Western countries had fallen by 59% between 1973 and 2011 . If this curve continues its current trajectory, she warns today, this figure could reach zero as early as 2045 . A form of "total" infertility which would not mean the end of births - in particular thanks to the development of PMA (medically assisted procreation) - but could reduce them drastically. " It's a little worrying, to say the least, " said Shanna H. Swan.
In detail, Count Down shows that it is the “ everyday chemicals ” found in food packaging, toys, cosmetics and even pesticides that have a lasting effect on our endocrine system. The phthalates and bisphenol A are more particularly targeted by the two authors " because they make the human body believe that it has enough hormones - testosterone or estrogen - and that it therefore does not need to manufacture them. more ”. The size and shape of the genitals would also be affected.
" Phthalates lower testosterone levels and therefore have a particularly bad influence on the male side, for example by causing a decrease in sperm count ," Swan explains in his interview with the Guardian. Bisphenol A, on the other hand, mimics estrogen and is therefore particularly harmful on the female side, increasing the risk of fertility problems. But it can also lower semen quality, sex drive, and cause higher rates of erectile dysfunction. "
"Much of the exposure to these materials occurs in utero, when the fetus is first formed"
The finding is all the more worrying as exposure to these substances begins ... even before birth. “ Much of the exposure to these materials occurs in utero, when the fetus is first formed. ,” says Swan. The effects then continue into childhood, adolescence and adulthood. It is a cumulative phenomenon: a female fetus, in utero, is already developing the eggs that it will use to have its own children. "
Proof of the extent of the problem, a survey published by Public Health France in 2019 revealed that the presence of bisphenols and phthalates in the body is generally greater in children than in adults. " Food would participate in 90% of the total exposure ," said Public Health France at the time. The only ways to minimize risk at the individual level, according to Shanna H. Swan: eat, " as far as possible ", unprocessed foods such as " naturally cooked carrots or potatoes "; avoid stoves that contain Teflon or toxic molecules; and “ do not microwave plastics ”.