Khaberni - Dr. Teresa Larkin, a professor at the University of Wollongong, reported that the number of sperm in semen begins to gradually decrease after the age of 20, and that by the age of 55, it approaches the threshold of infertility.
According to her, it's not just the number of sperm that matters, but also their quality. For pregnancy to occur successfully, the sperm must be alive, capable of movement, and of a normal shape. The volume of the seminal fluid, which provides nutrition and a means of transport for the reproductive cells, also plays a critical role in this process.
Teresa Larkin says: "Starting around the age of thirty, the proportion of motile sperm of normal shape begins to decrease, the volume of seminal fluid decreases, and these changes become more apparent after the age of thirty-five."
She added that studies involving more than two thousand couples have shown that men over the age of forty-five need, on average, five times longer to fertilize an egg compared to men under the age of twenty-five.
She points out that genetic damage accumulates in the sex cells with age, as the stem cells that produce sperm divide hundreds of times over the life of a man, and with each division, there is an increased risk of DNA errors, which can lead to stopped embryo growth or miscarriage.
She explains, "According to studies, if a woman conceives with a man older than forty, the risk of pregnancy loss is about 30% higher compared to those under the age of 29."
Moreover, after the age of thirty or forty, the rate of chromosomal abnormalities that can cause congenital disorders, including Down syndrome and Klinefelter syndrome, increases.
According to her, external factors also affect a man's fertility, as oxidative stress--characterized by an increase in harmful compounds with a lack of antioxidants--damages the DNA of sperm. This stress is exacerbated by air pollution, heavy metals, pesticides, as well as smoking, alcohol addiction, obesity, and lack of physical activity. Varicocele—a treatable dilation of the veins in the testicles—is also a common medical cause of infertility.
