Average Sperm Count Dropped 51.6% Between 1973 and 2018

In a review and meta-analysis published in Human Reproductive Update, researchers analyzed the variations in average global sperm count between 1973 and 2018. According to the publication, in addition to playing a role in fertility, sperm count may also be correlated with mortality and morbidity rates. Researchers found a 51.6% reduction in average sperm count worldwide between 1973 and 2018.

Researchers reviewed approximately 2,936 abstracts and 868 full articles. From these articles, they extrapolated 44 sperm concentrations and total sperm count estimates from 38 of the studies. The data were combined with a previous meta-analysis that collected 288 estimates from 223 studies. Using linear regression and weighted meta-regression analysis, researchers were able to chart and analyze changes in sperm count.

Investigators looked at two different geographic regions. The first region included North America, Europe, Australia, and New Zealand. This geographic region was referred to as NEA. They also looked at South America, Central America, Asia, and Africa, referred to as SAA.

Between 1973 and 2018, sperm concentration declined by –0.087 million/mL/year. Additionally, researchers noted that, across all continents, sperm concentration decreased by 51.6% in the researched time. Globally, the sperm count dropped from 104 million per mL in 1973 to 49 million per mL in 2018.

Additionally, the publication notes that the decline became steeper after 2000. In 1972, the decline per year was 1.16%. However, after 2000, the yearly decline was more than double that at 2.64%.

According to the Mayo Clinic, “Normal sperm densities range from 15 million to greater than 200 million sperm per mL of semen. You are considered to have a low sperm count if you have fewer than 15 million sperm per mL or less than 39 million sperm total per ejaculate.”

While the average male sperm count in 2018 was much lower than in 1973, it is still not considered low and is within the fertile range. Despite that, the current trajectory suggests that the global male sperm count will continue to decline, threatening the future of male reproductive health.

Many sources attribute decreased sperm count to chronic health problems, inherited conditions, injuries, or environmental factors. However, further research must be conducted to determine the causes of decreased sperm counts.