This section is written in partnership with UR Vistahermosa experts from Spain.

Factors that influence semen quality

Over the years, concern about semen quality has increased due to the decline in the seminal parameters established by the WHO. Although this decrease in values does not imply infertility, it translates into challenges to get pregnant.

The most common test to identify semen quality is a spermiogram, which measures:

  • Volume and pH
  • Sperm concentration in ejaculates (it should
  • be >15M/mL)
  • Sperm motility (above 32% motility)
  • Vitality (over 58% live sperm)
  • Morphology (at least 4% of sperm with normal
  • morphology)

In addition to this test, there is a series of complementary tests for a deeper analysis such as diagnostic capacitation, sperm fragmentation, or sperm FISH.

Which factors affect low semen quality?


Testosterone is an essential hormone, stimulating the testicle for spermatogenesis, which is the formation of sperm cells. When there is a high amount of adipose tissue, testosterone levels drop and estradiol levels peak, which inhibits spermatogenesis. A recent study published in the official journal of the American Society of Andrology, proved that men with a body mass index of over 25 kg/m2 present less mobile sperm cells in their ejaculates.


The relevance of women’s age for reproduction is well known, however it is little known in the case of men. The effect of men’s age on semen quality and reproductive function is controversial, since there is no universal definition for advanced paternal aging. Although it is true that if the man does not present a significant stop in spermatogenesis, as in the case of women and menopause, it has been observed that physiological aging of the masculine reproductive system can be manifested in different ways:

  1. Aging increases oxidative stress and this could cause cell damage, including DNA damage.
  2. With increasing age, semen volume progressively drops. This is due to aging of seminal vesicles, which produce the fluids that transport the sperm generated within the testes.
  3. A reduction of sperm motility has also been proven with the passage of years.
Factors that influence semen quality


Cigarettes include nicotine, alkaloids, amines, ketones, and other toxins. These compounds have alsobeen detected in seminal plasma, since they cross the blood-testicular barrier, influencing semen quality directly.

A study developed by the University of Saarland (Germany) has shown that men who smoke over a pack of cigarettes per day have 14% les protamine than non-smokers. Protamines are the proteins needed for sperm to work properly. They are located in the nucleus where DNA is concentrated and they protect them from possible damage and mutations. Protamine is essential for the creation of semen, wherefore its drop directly affects semen quality.

Article source:
This article has been published in Creando Familias magazine by UR Vistahermosa clinic from Spain.

Picture of Dr. Elisa Moya
Dr. Elisa Moya
Dr. Elisa Moya - UR Vistahermosa.

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