I thought you may be interested in this new study of 7,500 studies on trends in sperm counts that shows a significant ongoing decline, pointing to impaired male health and decreasing fertility. Researchers found that among men from North America, Europe and Australia, who were not selected for the study according to fertility status, sperm concentration and total sperm count has declined more than 50% in less than 40 years.
Media coverage included: Washington Post (https://www.washingtonpost.com/news/in-theory/wp/2017/07/25/your-sperm-is-in-trouble/?utm_term=.d5e06b304363) and Vice News (https://tonic.vice.com/en_us/article/9kw4yd/western-men-have-half-as-much-sperm-as-they-did-40-years-ago), among others.
The study, “Levine et al. Temporal trends in sperm count: A systematic review and meta-regression analysis” published in the peer-reviewed journal Human Reproduction Update yesterday. Please let me know if you would like a copy of the study or to speak with the authors.