Male fertility in decline, all over the world. This is revealed by a large study published this Tuesday in the journal Human Reproduction Update and carried out by compiling around forty previous studies on the subject. The concentration of spermatozoa, one of the factors of male fertility, has dropped markedly throughout the planet in recent decades. A first study from 2017 already affirmed this decline, but it focused only on Western countries, so it was strongly criticized.
Data from 1973 to 2018
This time, after integrating more data, the authors are able to conclude that the downward trend also concerns South America, Asia and Africa.
Researchers looked at data from 1973 to 2018 and one of the primary causes of this decline in fertility is the decline in sperm quality. The decrease in quantity of the latter is also underlined. The number of sperm available in semen has halved in 45 years.
Today, the concentration of gametes is 49 million per millilitre, compared to 101 million in 1973. Below 20 million sperm, the chances of having children are reduced.
Endocrine disruptors implicated
The decline in sperm quality can be explained, among other things, by exposure to certain toxic components. “Maternal tobacco will have an influence on the fertility of her son. Adult tobacco, overweight, but also exposure to certain pesticides or other everyday chemicals, such as phthalates, which are sometimes used to soften plastics or bisphenol A”, will have impacts on sperm, explains Rémy Slama is an epidemiologist, and director of the INSERM public health institute.
Exposure to these substances would also increase the risk of developing testicular cancer. The annual number of cases has doubled in 30 years. According to the epidemiologist, if men avoid endocrine disruptors and improve their lifestyle, the quality of their sperm could improve in a few years.