Semen quality is a measure of the ability of semen to accomplish fertilization. Thus, it is a measure of fertility in a man. It is the sperm in the semen that are of importance, and therefore semen quality involves both sperm quantity and quality. Decreased semen quality is a major factor of male infertility.

Contents 1 Tests 1.1 Semen analysis 1.2 Hamster zona-free ovum test 1.3 Sperm chromatin assay 2 Cryopreservation 2.1 Bad freezers 2.2 Sperm washing 3 Factors 3.1 Masturbation or intercourse 3.2 Heat 3.3 Physical trauma 3.4 Chemicals 3.4.1 Environmental chemicals 3.4.2 Medication 3.4.3 Hormones 3.4.4 Diet 3.4.5 Other chemicals 3.5 Last ejaculation 3.6 Environment 3.6.1 Outside body 3.6.2 In female 3.7 Home or in clinic 3.8 Mobile phones 3.9 Others 4 References

[edit] Tests

[edit] Semen analysis

A semen analysis typically measures the number of sperm per milliliter of ejaculate, and analyzes the morphology (shape) and motility (ability to swim forward) of the sperm. Also usually measured are the concentration of white blood cells, the level of fructose in the semen, and the volume, pH, and liquefaction time of the ejaculate.^[1][2]

A number of factors may influence the accuracy of semen analysis results, and results for a single man may have a large amount of natural variation over time.^[3] For this reason, a subfertile result must be confirmed with at least two further analyses.^[4]

[edit] Hamster zona-free ovum test

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. The human sperm does not fertilize the hamster eggs.^[5] A negative result on the hamster test correlates with a lower probability of the man's partner becoming pregnant.^[6]

[edit] Sperm chromatin assay

Chromatin is the complex of DNA and protein that make up chromosomes. If a large percentage of a man's sperm (greater than 30%) have damaged chromatin, his chances of impregnating a partner are significantly reduced, and if he does impregnate his partner, she faces an increased risk of miscarriage. The portion of a man's sperm with damaged chromatin may be determined with a Sperm Chromatin Structure Assay (SCSA).^[7]

[edit] 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 motility. If the grade of motility is poor, 10 million motile cells per ml is required.^[8]

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.^[9]

[edit] Bad freezers

In 10-20% of all men, the semen doesn't endure cryopreservation.^[8] The cause is unknown. It does not necessarily mean an otherwise bad semen quality.

[edit] 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.^[10]

[edit] Factors

There are many factors that influence the sperm quality. Exposure to any of them can cause up to a three month delay before sperm quality returns to normal, due to spermiogenesis.^[8]

[edit] Masturbation or intercourse

Sperm samples obtained via sexual intercourse contain 70^[11]-120^[12]% more sperm, with each sperm having a slightly higher^[13] motility and slightly more normal^[13] morphology, compared with sperm samples obtained via masturbation. Sexual intercourse also generates an 25-45%^[13] increase in ejaculate volume, mainly by increased prostate^[14] secretion.

This intercourse advantage is even greater for men with oligospermia.^[13]

However, the single factor or factors for the intercourse advantage have not yet been isolated. It can not be explained by presence of visual perception of physical attractiveness alone during stimulation,^[13][15] although there may be a slight correlation.^[16] Neither does any substantial fluctuations in sex hormones explain the intercourse advantage.^[14] It is hypothesized that sexual intercourse subdues an inhibition from the central nervous system^[13], but what, in turn, is the subduing factor is still not completely known. Stress to achieve ejaculation is suggested, as a shorter duration of stimulation before ejaculation decreases semen quality.^[17]

[edit] Heat

Sperm are heat-sensitive, and cannot endure too high temperatures. 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 of preventing infertility due to heat;

• sauna sessions^[8]
• bathing for a long time in hot water^[8]
• Long-time tanning bed sessions^[8]
• Tight^[8] and airtight trousers and underwear, since it hampers the sweating mechanism.

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

In the same way, sperm quality can be lower in the summer.^[8]

[edit] Physical trauma

A blow from outside doesn't affect the sperm quality of already produced sperm cells. Furthermore, the testes are well protected in the scrotum, for example by the tunica vaginalis, making the testes slide away from external pressure rather than being malformed from it. However a hard enough hit can close or crush the capilliaries that supply the sperm producing tissue, resulting in permanent or temporary partial or total inability to produce sperm in the affected testicle.

[edit] Chemicals

There is suspicion that many toxic substances, including several types of medication and hormones, and also constitutents of the diet, influence sperm quality^[8]. While a few chemicals with known effects on fertility have been excluded from human consumption, we cannot know if others remain undiscovered.

[edit] Environmental chemicals

There has been evidence for a general decline in sperm counts in Europe and the USA between 1938 and 1990.^[18] While these dates were critiqued, further analysis supported the findings.^[19][20] A 2008 report demonstrates further evidence of the effects of feminizing chemicals on male development in each class of vertebrate species as a worldwide phenomenon; these chemical are suspected of reducing the sex ratio and sperm counts in humans.^[21] Ninety-nine percent of over 100,000 recently introduced chemicals are poorly regulated.^[21]

At least three types of synthetic toxins have been found in the semen of student volunteers: polychlorinated biphenyls (PCBs), DDT, and hexachlorobenzene.^[22] Leaks of dibromochloropropane (DBCP) have caused sterility in men.^[22] Soldiers that were exposed to dioxin during the Vietnam war have given rise to children with an increased rate of birth defects.^[22] Plutonium, widely spread from nuclear weapon tests, accumulates in the testes, where it disrupts zinc metabolism, in turn causing genetic damage.^[22]

Phthalates, a ubiquitous pollutant, may cause decreased sperm production when having been exposed to it during prenatal development.^[23]

[edit] Medication

• 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 marijuana can confuse the movements of intact sperm, reducing their ability to achieve fertilization.^[24][25]

• Selective serotonin reuptake inhibitors (SSRI) may cause low sperm count.^[26]

• Many antibiotics, e.g. penicillin and tetracycline, suppress sperm production.^[22] It may indirectly reach humans through eating livestock given antibiotics as a growth promoter.

[edit] 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.^[8]

[edit] Diet

• Coffee and alcohol lowers the sperm quality. However, the influence is probably minor.^[8]

• Soy products decrease sperm quality due to content of isoflavones, a type of phytoestrogens.^[27][28] Theoretically, this exposure to high levels of phytoestrogen in men from soy products may alter the hypothalamic-pituitary-gonadal axis. Studies have shown that such a hormonal effect may be significant, and infertility may result.^[29] 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.^[30][31]

• Obesity increases risk of oligospermia and low motility by 300%,^[32] being overweight by 200%.^[32]

• Folate (vitamin B9) may protect sperm cells from aneuploidy.^[33]

[edit] Other chemicals

• Gossypol present in crude cottonseed oil (and potentially the organ meats from animals poisoned with it^[34]) has been associated with reduced sperm production. Misuse of anabolic steroids can cause testicular atrophy and reduced fertility.

[edit] Last ejaculation

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 reduces semen quality.

• A period of time of less than one day reduces sperm count by at least 20%.^[35]

• Longer periods of abstinence correlate with poorer results - one study^[36] found that men with repeated normal results from semen analysis produced abnormal samples if they abstained for more than 10 days. Another study^[36] found that couples where the man had abstained for more than 10 days before an intrauterine insemination (IUI) had only a 3% pregnancy rate. Daily sexual activity increases sperm quality in men with DNA damage in the sperm, and is thought to result from less storage time where damage may accumulate.^[37]

[edit] Environment

For semen that has been ejaculated, the quality deteriorates with time. However, this lifetime can be shortened or prolonged, depending on the environment.

[edit] Outside body

Sperm outside of the body generally has a life expectancy which is considered to depend on pH, temperature, presence of air and other factors, and is unpredictable but smaller than the life expectancy inside the human body.^{[citation needed]} For instance, sperm donors who collect the sample outside the clinic are advised to have handed in the sample before one hour from collection, and to keep them in, if not at body temperature, then at least at room temperature.^[38]

In a non-harmful environment outside the body, such as in a sterile glass container^[13] the number of motile sperm decreases with approximately 5-10%^[13] per hour. In contrast, in a latex condom, the quality decreases with 60-80%^[13] per hour, rendering the sample unusable in not too long time.

[edit] In female

The environment in the uterus and fallopian tubes are advantageous. A pregnancy resulting from sperm life of eight days has been documented.^[39][40][41]

[edit] Home or in clinic

The sperm quality is better if the sample is collected at home than in the booths in the clinics.^[42] Collecting the sperm at home gives a higher sperm concentration, sperm count and motility particularly if the sperm is collected via sexual intercourse.^[42]

[edit] Mobile phones

Having a mobile phone in talk mode in the pocket, like when using handsfree, has been suggested to be a risk if often used in the long-term.^[43]

In an in vitro study, sperm samples exposed to radio frequency electromagnetic waves (as in mobile phones) showed significantly decreased sperm motility and viability, increased ROS level, and decreased ROS-TAC score.^[44]

[edit] Others

Tobacco smoking lowers the sperm quality.^[22] However, the influence is probably minor.^[8] Smoking marijuana has similar effects.^[22] Long-term stress is also suggested.^[8]

Higher levels of intelligence are also correlated with higher levels of sperm quality in three key indicators: sperm concentration, sperm count and sperm motility. Men who scored high on a battery of intelligence tests tended to have higher counts of healthy sperm, while low scorers tended to have fewer and more sickly sperm. It is conceivable that intelligence might tip off a man's overall health to women looking for a mate with healthy genes, explained University of New Mexico evolutionary psychologist Geoffrey Miller at a talk at Harvard University. "Though the connections between brains and sperm were 'not awesome, they're there and highly significant,' Miller said. All things held equal, good sperm and good brains go together."^[45][46]

Regarding diet, malnutrition or an unhealthy diet can lead to e.g. Zinc deficiency, lowering sperm quality. Theoretically, a diet with low glycemic index would increase semen quality by providing an even supply of blood sugar, which is the major energy source for sperm cells. However, no trials have yet investigated the role of glycemic index on semen quality.^{[citation needed]}

Sperm quality is better in the afternoon than in the morning.^[47] Adrenaline-levels are higher during awakening (~06.00 to noon),^[48] 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.^[49]

A longer duration of sexual stimulation before ejaculation slightly increases sperm quality.^[50]

Several studies have suggested a population-wide decline in the quality of semen over the past 50 years, but clear evidence for decreasing semen quality in recent decades is lacking.^[51]

[edit] References