The good news: The male population of France is still fertile. The bad: Its sperm isn't nearly what it once was. A 16-year study of 26,600 of the country's men found their sperm count has sharply fallen, with the number of millions of spermatozoa per milliliter down 1.9% a year—or a staggering 32.3% over the course of the study. If that sounds worrying to you, you're not alone: "This constitutes a serious public health warning," the researcher tells the BBC. The average concentration in a 35-year-old male now stands at 49.9 million per milliliter; still well above the 15 million-per-milliliter threshold that typically signifies infertility, but the researcher says those below the 55 million mark can find it takes longer to conceive.
The study also found that the percentage of normally formed sperm in the men's semen fell 33.4%. LiveScience reports that the technology used to measure sperm shape has gotten more precise, but that can't account for the entirety of the deterioration. It's unclear what is causing the degradation, but one professor posits that it's "something in our modern lifestyle, diet, or environment like chemical exposure." The BBC notes that while the study did consider factors like age in its analysis, it didn't control for socio-economic factors that can affect sperm quality, like smoking or weight. (Read more sperm stories.)