22/09/2025
S***m parameters are the specific characteristics of semen evaluated during a semen analysis to assess male fertility. The main parameters include s***m concentration (number of s***m per milliliter), s***m motility (proportion of s***m that are swimming), s***m morphology (the shape of the s***m), semen volume, and semen vitality (the proportion of live s***m). Other parameters include pH, viscosity, and the presence of leukocytes.
S***m values, particularly s***m concentration and count, have declined significantly worldwide since the 1980s, with some studies reporting a drop of over 50% in Western countries between the 1970s and 2015, though data is heterogeneous and causes are complex, involving environmental factors like endocrine-disrupting chemicals, lifestyle changes, and obesity.
The general gist
Significant Decline
1. Multiple meta-analyses and studies have documented a global trend of decreasing s***m concentration and count over the last few decades.
Regional Differences
2. While a global decline is observed, the rates of decline vary by geographical region, with steeper declines seen in Western countries compared to non-Western countries.
3. A 2022 meta-analysis reported a 53.3% decline in s***m concentration and a 56.3% decline in s***m count in Western countries between 1973 and 2015.
4. Exposure to industrial chemicals, pesticides, endocrine-disrupting chemicals, and heavy metals is linked to reduced s***m quality.
5. Lifestyle factors such as obesity, sedentary habits, diet changes (the “nutrition transition”), and even air pollution are considered contributing factors.
