What’s happening: In 2017, Mt. Sinai Medical School epidemiologist Shanna Swan co-authored a sweeping meta-analysis that came to a startling conclusion: Total sperm count in the Western world had fallen 59% between 1973 and 2011.
Together with falling testosterone levels and growing rates of testicular cancer and erectile dysfunction, that translated into a 1% increase per year of adverse reproductive changes for men, according to Swan.
Driving the news: Now Swan has written up her conclusions in a new book with a foreboding title: “Count Down: How Our Modern World Is Threatening Sperm Counts, Altering Male and Female Reproductive Development, and Imperiling the Future of the Human Race.”
“If you look at the curve on sperm count and project it forward — which is always risky — it reaches zero in 2045,” says Swan, meaning the median man would have essentially no viable sperm. “That’s a little concerning, to say the least.”
By the numbers: The global fertility rate — the number of births per woman — has fallen from 5.06 in 1964 to 2.4 in 2018.
Today, about half the countries in the world — including the U.S. — have fertility rates below the population replacement level of 2.1 births.
By 2050, that proportion is projected to rise to two-thirds of nations.
Yes, but: There are numerous factors connected to falling fertility rates that appear largely unconnected to sperm counts.