Semen quality is determined by the ability to potentially fertilize an egg, and is generally determined by measuring the amount of sperm in a sample, their shape, and their ability to move forward. There are many different factors that can influence semen quality, including lifestyle, environment, and medical causes. Age is also an important factor in reduced fertilization capabilities, as most men experience a gradual drop in semen quality as they get older.
Lifestyle factors can be important contributors to the quality of semen. Some medical studies have found that men with poor dietary habits, especially those who are obese, can have a significant reduction in sperm count and quality. Evidence also suggests that excessive use of alcohol, smoking, or the use of certain prescription or illegal drugs can also be an important factor in reduced fertility. Some doctors also consider depression and emotional stress to be possible contributing influences to lower sperm count or other reproductive issues. A healthy diet and regular exercise are both linked to better semen quality.
The full effects of environmental factors on male fertility are still quite unknown. Certain environmental conditions, such as exposure of the genitals to excessive heat, are clearly shown to be linked to fertility problems. Exposure to radiation can also result in an increase of incorrectly shaped or immobile sperm, and may reduce sperm count for several months or years. Other environmental factors, such as pesticide and chemical exposure, may result in significant fertility decreases, but these effects have not been fully investigated.
Medical factors can play an important role in male fertility. Men with functional deformities, such as improperly shaped sperm ducts or undescended testicles can have low sperm quality. Certain diseases, such as testicular cancer or gluten allergies can also negatively affect sperm count and quality. Natural or medication-induced hormonal imbalances can result in lower sperm production, which may be corrected with fertility treatments. The use of steroids, cancer drugs, and even some antibiotics can also reduce fertility levels.
While many lifestyle, environmental, and medical factors that decrease semen quality can be treated and corrected, one major determining factor that cannot be ignored is the aging process. As men age, sperm count and motility tend to decrease, while morphology may become more irregular. Most men do not experience a significant change until their mid-30s, but some studies have shown minor decreases in men in their 20s as well. Older men struggling with fertility issues may want to visit a reproductive specialist to determine the best path to maximizing fertilization.