Semen quality

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Semen quality is a measure of male fertility, a measure of the ability of sperm in semen to accomplish fertilization. Semen quality involves both sperm quantity and quality. Semen quality is a major factor for fertility.

Contents

An amount of human semen of unknown quality. Semen 030.JPG
An amount of human semen of unknown quality.

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. [2] Advancing paternal age has been implicated in a number of possible health effects. One particularly well-studied connection is the link between advancing age and autism. For example, one study of 943,664 children less than 10 years old found that, with confounding variables controlled, the risk of autism increased with increasing paternal age. [3]

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

A man using a laptop which is placed above his groin. The heat of which may interfere with the quality of his semen. Computadoras y Obesidad.jpg
A man using a laptop which is placed above his groin. The heat of which may interfere with the quality of his semen.

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:

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 man getting kicked in the scrotum, causing physical trauma to the testicles Groin Kick Self-defense.jpg
A man getting kicked in the scrotum, causing physical trauma to the testicles

A blow from outside does not 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 capillaries that supply the sperm producing tissue, resulting in permanent or temporary and partial or total inability to produce sperm in the affected testicle.

Chemicals

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

Endocrine disruptors are chemicals that interfere with the endocrine (hormone) system.

A 2008 report demonstrated 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. [9] Ninety-nine percent of over 100,000 recently introduced chemicals[ vague ] are poorly regulated. [9]

At least three types of synthetic toxins have been found in the semen of student volunteers: polychlorinated biphenyls (PCBs), DDT, and hexachlorobenzene. [10] DDT and hexachlorobenzene are associated with decreased semen quality, while PCBs are associated with decreased fertility overall. [8] Leaks of dibromochloropropane (DBCP) have caused sterility in men. [10] Soldiers that were exposed to dioxins and dioxin-like compounds during the Vietnam war have given rise to children with an increased rate of birth defects. [10]

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 bisphenol A, nonylphenol and octylphenol. [8]

Medication

A man smoking a marijuana joint containing THC which can have a negative impact on semen quality. Cannabis user.jpg
A man smoking a marijuana joint containing THC which can have a negative impact on semen quality.

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

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

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:

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 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 intrauterine insemination (IUI) had only a 3% pregnancy rate. An abstinence period of only 1 or 2 days produce the highest pregnancy rates per IUI cycle compared with longer intervals of ejaculatory abstinence. [28] This increase in pregnancy rate occurs despite a lower value of total motile spermatozoa. [28] Daily sexual activity increases sperm quality in men minimizing DNA damage in the sperm—because it is speculated to result in less storage time where damage may accumulate. [29]

Masturbation vs intercourse

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 physical attractiveness alone during stimulation, [32] [34] although there may be a slight correlation. [35] Neither do any substantial fluctuations in sex hormones explain the intercourse advantage. [33] It is hypothesized that sexual intercourse subdues an inhibition from the central nervous system, [32] but what, in turn, is the subduing factor is still not completely known.

Home or in clinic

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 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 no more than one hour from collection, and to keep it, if not at body temperature, then at least at room temperature. [37]

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

Tobacco smoking lowers the sperm quality, [10] perhaps by decreased ability to attach to hyaluronan on the egg cell. [41] Wright et al. [6] have reviewed evidence that smoking is associated with increased sperm DNA damage and male infertility. Smoking cannabis can decrease sperm quantity. [10]

Long-term stress is also suggested. The practise of tucking can reduce both the sperm count and sperm quality. [42] Meta-analysis indicates that mobile phone exposure affects sperm quality negatively. [43]

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 millilitre of ejaculate, and analyzes the morphology (shape) and motility (ability to swim forward) of the sperm (the typical ejaculate of a healthy, physically mature young adult male of reproductive age with no fertility-related problems usually contains 300–500 million spermatozoa, though only a couple of hundred survive in the acidic environment of the vagina to be candidates for successful fertilization). 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. [50] [51]

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. [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 antisperm antibodies may be responsible for sperm agglutination, reduced sperm motility, abnormal postcoital test. Several tests are presently available including sperm immobilization test, sperm agglutination tests, indirect immunofluorescence test, enzyme-linked immunosorbent assay, radiolabelled antiglobulin assay. One of the most informative and specific tests is immunobead rosette test which can identify different antibody classes involved (IgG, IgA, IgM) and location on the sperm cell (head, body or tail). [55]

Hemizona test

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

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

Related Research Articles

<span class="mw-page-title-main">Intracytoplasmic sperm injection</span> In vitro fertilization procedure

Intracytoplasmic sperm injection is an in vitro fertilization (IVF) procedure in which a single sperm cell is injected directly into the cytoplasm of an egg. This technique is used in order to prepare the gametes for the obtention of embryos that may be transferred to a maternal uterus. With this method, the acrosome reaction is skipped.

<span class="mw-page-title-main">Infertility</span> Inability to reproduce by natural means

Infertility is the inability of a couple to reproduce by natural means. It is usually not the natural state of a healthy adult. Exceptions include children who have not undergone puberty, which is the body's start of reproductive capacity. It is also a normal state in women after menopause.

<span class="mw-page-title-main">Personal lubricant</span> Substance to reduce friction, usually during sexual acts

Personal lubricants are specialized lubricants used during sexual acts, such as intercourse and masturbation, to reduce friction to or between the penis and vagina, anus or other body parts or applied to sex toys to reduce friction or to ease penetration. As of 2015, the personal lubricant market was estimated to be worth at least $400 million.

Fertility medications, also known as fertility drugs, are medications which enhance reproductive fertility. For women, fertility medication is used to stimulate follicle development of the ovary. There are very few fertility medication options available for men.

<span class="mw-page-title-main">Semen collection</span> Process of obtaining semen from male animals

Semen collection refers to the process of obtaining semen from human males or other animals with the use of various methods, for the purposes of artificial insemination, or medical study. Semen can be collected via masturbation, prostate massage, artificial vagina, penile vibratory stimulation (vibroejaculation) and electroejaculation. Semen can be collected from endangered species for cryopreservation of genetic resources.

<span class="mw-page-title-main">Sperm bank</span> Facility that allocates human semen

A sperm bank, semen bank, or cryobank is a facility or enterprise which purchases, stores and sells human semen. The semen is produced and sold by men who are known as sperm donors. The sperm is purchased by or for other persons for the purpose of achieving a pregnancy or pregnancies other than by a sexual partner. Sperm sold by a sperm donor is known as donor sperm.

Terms oligospermia, oligozoospermia, and low sperm count refer to semen with a low concentration of sperm and is a common finding in male infertility. Often semen with a decreased sperm concentration may also show significant abnormalities in sperm morphology and motility. There has been interest in replacing the descriptive terms used in semen analysis with more quantitative information.

Hypospermia is a condition in which a man has an unusually low ejaculate volume, less than 1.5 mL. It is the opposite of hyperspermia, which is a semen volume of more than 5.5 mL. It should not be confused with oligospermia, which means low sperm count. Normal ejaculate when a man is not drained from prior sex and is suitably aroused is around 1.5–6 mL, although this varies greatly with mood, physical condition, and sexual activity. Of this, around 1% by volume is sperm cells. The U.S.-based National Institutes of Health defines hypospermia as a semen volume lower than 2 mL on at least two semen analyses.

Male infertility refers to a sexually mature male's inability to impregnate a fertile female. In humans, it accounts for 40–50% of infertility. It affects approximately 7% of all men. Male infertility is commonly due to deficiencies in the semen, and semen quality is used as a surrogate measure of male fecundity. More recently, advance sperm analyses that examine intracellular sperm components are being developed.

Asthenozoospermia is the medical term for reduced sperm motility. Complete asthenozoospermia, that is, 100% immotile spermatozoa in the ejaculate, is reported at a frequency of 1 of 5000 men. Causes of complete asthenozoospermia include metabolic deficiencies, ultrastructural abnormalities of the sperm flagellum and necrozoospermia.

<span class="mw-page-title-main">Semen analysis</span> Scientific analysis of semen

A semen analysis, also called seminogram or spermiogram, evaluates certain characteristics of a male's semen and the sperm contained therein. It is done to help evaluate male fertility, whether for those seeking pregnancy or verifying the success of vasectomy. Depending on the measurement method, just a few characteristics may be evaluated or many characteristics may be evaluated. Collection techniques and precise measurement method may influence results. The assay is also referred to as ejaculate analysis, human sperm assay (HSA), sperm function test, and sperm assay.

<span class="mw-page-title-main">Sperm motility</span> Process involved in the controlled movement of a sperm cell

Sperm motility describes the ability of sperm to move properly through the female reproductive tract or through water to reach the egg. Sperm motility can also be thought of as the quality, which is a factor in successful conception; sperm that do not "swim" properly will not reach the egg in order to fertilize it. Sperm motility in mammals also facilitates the passage of the sperm through the cumulus oophorus and the zona pellucida, which surround the mammalian oocyte.

Teratospermia or teratozoospermia is a condition characterized by the presence of sperm with abnormal morphology that affects fertility in males.

<span class="mw-page-title-main">Ejaculation</span> Semen discharge from the male reproductive tract

Ejaculation is the discharge of semen from the testicles through the penis and out the urethra. It is the final stage and natural objective of male sexual stimulation, and an essential component of natural conception. After forming an erection, many men emit pre-ejaculatory fluid during stimulation prior to ejaculating. Ejaculation involves involuntary contractions of the pelvic floor and is normally linked with orgasm. It is a normal part of male human sexual development.

Semen cryopreservation is a procedure to preserve sperm cells. Semen can be used successfully indefinitely after cryopreservation. It can be used for sperm donation where the recipient wants the treatment in a different time or place, or as a means of preserving fertility for men undergoing vasectomy or treatments that may compromise their fertility, such as chemotherapy, radiation therapy or surgery. It is also often used by trans women prior to medically transitioning in ways that affect fertility, such as feminizing hormone therapy and orchiectomies.

<span class="mw-page-title-main">Fertility testing</span> Process for assessing human fertility

Fertility testing is the process by which fertility is assessed, both generally and also to find the "fertile window" in the menstrual cycle. General health affects fertility, and STI testing is an important related field.

Obesity is defined as an abnormal accumulation of body fat, usually 20% or more over an individual's ideal body weight. This is often described as a body mass index (BMI) over 30. However, BMI does not account for whether the excess weight is fat or muscle, and is not a measure of body composition. For most people, however, BMI is an indication used worldwide to estimate nutritional status. Obesity is usually the result of consuming more calories than the body needs and not expending that energy by doing exercise. There are genetic causes and hormonal disorders that cause people to gain significant amounts of weight but this is rare. People in the obese category are much more likely to suffer from fertility problems than people of normal healthy weight.

Antisperm antibodies (ASA) are antibodies produced against sperm antigens.

The male infertility crisis is an increase in male infertility since the mid-1970s. The issue attracted media attention after a 2017 meta-analysis found that sperm counts in Western countries had declined by 52.4 percent between 1973 and 2011. The decline is particularly prevalent in Western countries such as New Zealand, Australia, Europe, and North America. A 2022 meta-analysis reported that this decline extends to non-Western countries, namely those in Asia, Africa, Central America, and South America. This meta-analysis also suggests that the decline in sperm counts may be accelerating.

<span class="mw-page-title-main">Sperm Chromatin Structure Assay</span>

Sperm Chromatin Structure Assay (SCSA) is a diagnostic approach that detects sperm abnormality with a large extent of DNA fragmentation. First described by Evenson in 1980, the assay is a flow cytometric test that detects the vulnerability of sperm DNA to acid-induced denaturation DNA in situ. SCSA measures sperm DNA fragmentation attributed to intrinsic and extrinsic factors and reports the degree of fragmentation in terms of DNA Fragmentation Index (DFI). The use of SCSA expands from evaluation of male infertility and subfertility, toxicology studies and evaluation of quality of laboratory semen samples. Notably, SCSA outcompetes other convention sperm DNA fragmentation (sDF) assays such as TUNEL and COMET in terms of efficiency, objectivity, and repeatability.

References

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  22. ↑ Folate 'may keep sperm healthy' BBC News. Last Updated: Thursday, 20 March 2008, 04:39 GMT
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