Semen quality

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Semen quality is a measure of male

Cryptorchidism, hypospadias, testicular cancer and poor semen quality make up the syndrome known as testicular dysgenesis syndrome.

Factors

There are many factors that influence the sperm quality. Exposure to any of the temporary factors can cause up to a three-month delay before sperm quality returns to normal, due to spermiogenesis.

General decline

A 2017 review and meta-analysis found sperm counts among Western men (i.e. men in Australia, Europe, New Zealand, and North America) declined 50–60% between 1973 and 2011, with an average decline of 1.4% per year. The meta-analysis found no indication the decline is leveling off. The amount of decline among men in North America and men in Australia/Europe is similar. The decline in sperm count among men in South America, Asia, and Africa is less than men in Western countries, though the amount of decline in these regions is uncertain. Reasons for the decline are not known with certainty, but it may be associated with chemical exposure, maternal smoking during prenatal development, pesticide exposure, or lifestyle changes during adulthood.^[1]

Age

Although it is possible for men to father children into old age, the genetic quality of sperm, as well as its volume and motility, all typically decrease with age.

In men with a normal level of sperm production (normozoospermia), the percentage of sperm DNA fragmentation is positively correlated with age, and inversely correlated with progressive sperm motility.^[4] No age related effects on sperm were noted in separate control groups recruited in different geographical locations, indicating that dietary habits, lifestyle or ethnicity could play a part in the quality of sperm.

While advanced age can be a possible factor in sperm motility and health, the sperm of men below 20 years of age has likewise been linked to an increase in birth defects such as neural tube defects, hypospadias, cystic kidney, and Down syndrome.^[5]

Heat

Sperm are heat-sensitive, and cannot endure high temperatures. Increases of 2–3 °C are associated with increased DNA fragmentation.^[6] The body has compensatory mechanisms, like the cremaster muscle relaxing and letting the testicle hang further away from the warm body, sweating and a countercurrent exchange of blood cooling inflowing blood. However, despite these compensations, there are activities that should not be performed too often, in order to prevent infertility due to heat:

• sauna sessions
• bathing for a long time in hot water
• Long-time
  tanning bed
  sessions
• Placement of a laptop computer over the groin for extended use

Fever raises the body temperature, which can strike sperm quality.

Contrary to widely held beliefs, no evidence supports that wearing tight underpants decreases fertility. Even with an elevation in temperature of 0.8–1° caused by wearing constrictive underwear, no changes in sperm parameters, no decrease in spermatogenesis, and no changes in sperm function are observed.^{[7][dubious – discuss]}

Physical trauma

A blow from outside does not affect the sperm quality of already produced sperm cells. Furthermore, the

There is suspicion that many toxic substances, including several types of medication and hormones, and also constituents of the diet, influence sperm quality. While a few chemicals with known effects on fertility have been excluded from human consumption, we cannot know if others remain undiscovered. Many products that come into direct contact with spermatozoa lack adequate testing for any adverse effect on semen quality.[8]

Endocrine disruptors

A 2008 report demonstrated evidence of the effects of

Phthalates, a ubiquitous pollutant, may cause decreased sperm production when having been exposed to it during prenatal development.^[8][11]

Other potential xenoestrogens that have been associated with decreased sperm quality in some studies are

• Depo-Provera, Adjudin, and gossypol are examples of substances used as male contraceptives or in chemical castration. Recent studies have found that THC present in cannabis can confuse the movements of intact sperm, reducing their ability to achieve fertilization.^[12][13]
• Selective serotonin reuptake inhibitors (SSRI) may cause low sperm count.^[14]
• Many antibiotics, e.g., penicillin and tetracycline, suppress sperm production.^[10]

In addition, in vitro studies have observed altered sperm function by the following medications:

• Many
  antiepileptics (e.g., lithium), and propranolol^[8]
• Opioid analgesics^[8]
• Calcium channel blockers^[8]
• Phosphodiesterase inhibitors (e.g., caffeine, theophylline, pentoxifylline)^[8]
• Statins^[8]
• Calcium
  EDTA)^[8]

Also, numerous products that are intended for exposure to spermatozoa have only a general assumption of safety based on the absence of evidence of actual harm.[8]

Hormones

• Anabolic steroids use and use of other hormones can reduce sperm quality. Changes in hormone homeostasis affect the spermatogenesis.

The body also has natural variations in hormone concentrations, giving sperm quality natural fluctuations as well.^{[citation needed]}

Diet

• Drinking over 1 litre of cola a day might decrease sperm quality by up to 30%^[15] (study claims there is correlation, but not causation)
• Soy products decrease sperm quality due to the high content of a type of phytoestrogen called isoflavones.^[16][17] Theoretically, this exposure to high levels of phytoestrogen in men may alter the hypothalamic-pituitary-gonadal axis. A few studies on animals have shown that such a hormonal effect may be significant and decrease fertility.^[18] On the other hand, most studies have shown that isoflavone supplements have little to no effect on sperm concentration, count, or mobility, and cause no changes in testicular or ejaculate volume.^[19][20]
• A review in 2010 concluded that there is little evidence for a relationship with semen parameters and increased BMI.^[21]
• Folate (vitamin B₉) may protect sperm cells from aneuploidy.^[22]
• Gossypol has been associated with reduced sperm production. It is present in crude cottonseed oil, and potentially the organ meats from animals poisoned with it^[23]
• Recently, a review of epidemiological/observational studies provided the most comprehensive analysis to date of the associations between diet or nutrient intake and the risk of infertility. It suggests that diet modifications may be useful in modulating male fertility and fecundability. Healthy diets (i.e. the Mediterranean diet) rich in such nutrients as omega-3 fatty acids, some antioxidants and vitamins, and low in saturated fatty acids (SFAs) and trans-fatty acids (TFAs) are associated with high semen quality parameters. In terms of food groups, fruit, seafood, poultry, eggs, cereals, leafy vegetables, dark chocolate, and low-fat dairy products have been positively related to sperm quality. However, diets rich in processed meat, fried foods, potatoes, full-fat dairy products, caffeine, alcohol and sugar-sweetened beverages have been inversely associated with the quality of semen in some studies. The few studies relating male nutrient or food intake and fecundability also suggest that diets rich in red meat, processed meat, tea and caffeine are associated with a lower rate of fecundability. This association is only controversial in the case of coffee, because a little bit of coffee, two to three cups a day, has been shown to help improving sperm motility, but more than three cups a day have been shown to have impaired fertility.^[24] The potential biological mechanisms linking diet with sperm function and fertility are largely unknown and require further study.^[25]
• One study found that following a diet rich in fruits, vegetables, potatoes, meat, full-fat dairy products, seafood and pastries increased sperm count by 50%. Men who consume such diet have sperm counts nearly twice as high as men who do not.^[26]

Other chemicals

Environmental mutagens that are associated with decreased semen quality include the following:

• Plutonium, widely spread from nuclear weapon tests, accumulates in the testes, where it disrupts zinc metabolism, in turn causing genetic damage.^[10]
• Ethylene oxide, a chemical sterilizer, is associated with decreased semen quality.^[8]

Other environmental agents associated with decreased semen quality include:

• Sertoli cells, thereby impeding spermatogenesis.^[8]
• Lead, causing reduced spermatogenesis and abnormal spermatozoa.^[8]
• Mercury, being highly damaging to spermatogenesis.^[8]
• Many
  chromosome anomalies.^[8]
• Polybrominated diphenyl ethers (PBDEs).^[8]
• Many
  perchloroethylene, trichloroethylene.^[8]

How long the man has abstained prior to providing a semen sample correlates with the results of semen analysis and also with success rates in assisted reproductive technology (ART).

Both a too short period of time since last ejaculation and a too long one reduce semen quality.

A period of time of less than one day reduces sperm count by at least 20%.^[27]

Longer periods of abstinence correlate with poorer results—one study found that couples where the man had abstained for more than 10 days before an

Semen samples obtained via sexual intercourse contain 70^[30]–120^[31]% more sperm, with sperm having a slightly higher^[32] motility and slightly more normal^[32] morphology, compared with semen samples obtained via masturbation. Sexual intercourse also generates a 25–45%^[32] increase in ejaculate volume, mainly by increased prostate^[33] secretion.

This intercourse advantage is even greater for men with oligospermia.^[32]

However, the single factor or factors for the intercourse advantage have not yet been isolated. It cannot be explained by presence of visual perception of

Sperm quality is higher when a sample is collected at home than in a clinic.[36] Collecting the sperm at home gives a higher sperm concentration, sperm count and motility, particularly if the sperm is collected via sexual intercourse.^[36] If the semen sample is to be collected by masturbation, a specimen from the early stages of the ejaculate should be into a clean, unused, sealed collection cup.

Environment

For semen that has been ejaculated, the quality deteriorates with time. However, this lifetime can be shortened or prolonged, depending on the environment.^{[citation needed]}

Outside body

Sperm outside the body generally has a life expectancy which is considered to depend on

In a non-harmful environment outside the body, such as in a sterile glass container[32] the number of motile sperm decreases by approximately 5–10%^[32] per hour. In contrast, in a latex condom, the quality decreases by 60–80%^[32] per hour, rendering the sample unusable in a relatively short time.

In female

The environment in the uterus and fallopian tubes is advantageous. A pregnancy resulting from sperm life of eight days has been documented.^[38][39][40]

Others

Long-term

Regarding diet, malnutrition or an unhealthy diet can lead to e.g. Zinc deficiency, lowering sperm quality.

Sperm quality is better in the afternoon than in the morning.^[44] Adrenaline-levels are higher during awakening (~06.00 to noon),^[45] which may contribute similarly to general stress.

Lack of exercise, as well as excessive exercise, are minor factors. In professional sports, semen quality parameters tend to decrease as training requirements increase. The effect differs substantially between different professional sport types. For example, water polo appears substantially less harmful to semen quality than triathlon.^[46]

A longer duration of sexual stimulation before ejaculation slightly increases sperm quality.^[47]

Males carrying Robertsonian translocations in their chromosomes have significantly higher degree of sperm cell apoptosis and lower concentration. Sperm cells also have decreased forward motility, but normal morphology.^[48]

Testicular cancer, Leydig cell tumours and Sertoli cell tumours are also associated with reduced sperm count and quality.^[49]

Tests

Semen analysis

A semen analysis typically measures the number of sperm per

A man's sperm are mixed with hamster eggs that have had the zona pellucida (outer membranes) removed, and the number of sperm penetrations per egg is measured.^[52] No strong correlation has been found between hamster egg penetration rates and the various semen parameters and the role of the hamster egg penetration test in the investigation of the causes of infertility should be evaluated further.^[53] However, a negative result on the hamster test correlates with a lower probability of the man's partner becoming pregnant.^[54]

Antisperm antibodies test

Presence of

Hemizona test is a test to evaluate sperm zona-binding capacity. In this test, the two halves of human zona pellucida is incubated with patient's capacitated sperm and control fertile donor's sperm.[55]

Other tests

• PCR-based detection of the pathogens in the semen of patients with asymptomatic genital infection.^[55]
• Biochemical markers like creatine kinase, Reactive oxygen species.^[55]

Cryopreservation

When performing cryopreservation of semen, it is the sperm quality after reviving the sample that is of importance, because many sperm cells die in the process.

To be of use in assisted reproductive technology, the sample should after thawing have more than 5 million motile sperm cells per ml with a good grade of mobility. If the grade of mobility is poor, 10 million motile cells per ml is required.

Home insemination of previously frozen sperm can be accomplished with the use of a cervical cap conception device as a delivery system for the sperm.^[56]

Bad freezers

In 10–20% of all men, the semen does not endure cryopreservation. The cause is unknown. It does not necessarily mean an otherwise bad semen quality.

Sperm washing

When a sperm sample is prepared for intrauterine insemination, it is washed at a facility such as a fertility clinic or a sperm bank. Some sperm does not survive the washing process, as is also the case when freezing the sperm.

See also

• Male infertility crisis
• Ovum quality
• Semen analysis

References