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By the 2010s, it was clear that there had been a significant, steady decline in sperm count and semen volume. A 2017 meta-analysis led by Hagai Levine from the Hebrew University reported decreases in sperm concentration of 52.4 percent and in sperm count of 59.3 percent, from 1973 to 2011 in Western countries (Australia, New Zealand, Europe ...
For example, males who are at a higher risk of sperm competition (defined as having female partners with high reproductive value, such as being younger and physically attractive) engaged more frequently in semen-displacing behaviors during sexual intercourse than men who were at a lower risk of sperm competition. [22]
To get that value, two different variables are multiplied: sperm concentration—the number of sperm per millimeter of semen—and semen volume, which is exactly what it sounds like.
Collecting the sperm at home gives a higher sperm concentration, sperm count, and motility, particularly if the sperm is collected via sexual intercourse. [35] If the semen sample is to be collected by masturbation, a specimen from the early stages of the ejaculation should be placed into a clean, unused, sealed collection cup.
Sperm count declines with age, with men aged 50–80 years producing sperm at an average rate of 75% compared with men aged 20–50 years. However, an even larger difference is seen in how many of the seminiferous tubules in the testes contain mature sperm: In males 20–39 years old, 90% of the seminiferous tubules contain mature sperm.
Sperm count is determined with a simple test called a semen analysis that looks at sperm concentration, or how many sperm there are per milliliter of fluid. There should be about 100,000,000 sperm ...
Males from India had a 30.3% decline in sperm count, 22.9% decline in sperm motility, and a 51% decrease in morphology over a span of a decade. Doctors in India disclosed that the sperm count of a fertile Indian male had decreased by a third over a span of three decades. [80]
Sperm competition is where the sperm of two males simultaneously occupy the reproductive tract of a female and they compete to fertilise the egg. [32] If sperm competition results in the rival male's sperm fertilising the egg, cuckoldry could occur. This is the process whereby males unwittingly invest their resources into offspring of another ...