Semen quality
Semen quality is a measure of the ability of semen
Semen is an organic fluid, also known as seminal fluid, that may contain spermatozoa. It is secreted by the gonads and other sexual organs of male or hermaphroditic animals and can fertilize female ova...

 to accomplish fertilization. Thus, it is a measure of fertility
Fertility is the natural capability of producing offsprings. As a measure, "fertility rate" is the number of children born per couple, person or population. Fertility differs from fecundity, which is defined as the potential for reproduction...

 in a man
The term man is used for an adult human male . However, man is sometimes used to refer to humanity as a whole...

. 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
Male infertility
Male infertility refers to the inability of a male to achieve a pregnancy in a fertile female. In humans it accounts for 40-50% of infertility. Male infertility is commonly due to deficiencies in the semen, and semen quality is used as a surrogate measure of male fecundity.-Pre-testicular...


Semen analysis

A semen analysis typically measures the number of sperm per milliliter of ejaculate, and analyzes the morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....

 (shape) and motility
Motility is a biological term which refers to the ability to move spontaneously and actively, consuming energy in the process. Most animals are motile but the term applies to single-celled and simple multicellular organisms, as well as to some mechanisms of fluid flow in multicellular organs, in...

 (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 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
Fructose, or fruit sugar, is a simple monosaccharide found in many plants. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into the bloodstream during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847...

 in the semen, and the volume
Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance or shape occupies or contains....

, pH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...

, and liquefaction
In physics, to liquefy means to turn something into the liquid state.-In Geology:In geology, liquefaction refers to the process by which saturated, unconsolidated sediments are transformed into a substance that acts like a liquid.Earthquakes can cause soil liquefaction where loosely packed,...

 time of the ejaculate.

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. For this reason, a subfertile result must be confirmed with at least two further analyses.

Hamster zona-free ovum test

A man's sperm are mixed with hamster
Hamsters are rodents belonging to the subfamily Cricetinae. The subfamily contains about 25 species, classified in six or seven genera....

 eggs that have had the zona pellucida
Zona pellucida
The zona pellucida is a glycoprotein membrane surrounding the plasma membrane of an oocyte. It is a vital constitutive part of the latter, external but of essential importance to it...

 (outer membranes) removed, and the number of sperm penetrations per egg is measured. The human sperm does not fertilize the hamster eggs. A negative result on the hamster test correlates with a lower probability of the man's partner becoming pregnant.

Sperm chromatin assay

Chromatin is the combination of DNA and proteins that make up the contents of the nucleus of a cell. The primary functions of chromatin are; to package DNA into a smaller volume to fit in the cell, to strengthen the DNA to allow mitosis and meiosis and prevent DNA damage, and to control gene...

 is the complex of DNA and protein that make up chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...

s. 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
Miscarriage or spontaneous abortion is the spontaneous end of a pregnancy at a stage where the embryo or fetus is incapable of surviving independently, generally defined in humans at prior to 20 weeks of gestation...

. The portion of a man's sperm with damaged chromatin may be determined with a Sperm Chromatin Structure Assay (SCSA).


When performing cryopreservation
Cryopreservation is a process where cells or whole tissues are preserved by cooling to low sub-zero temperatures, such as 77 K or −196 °C . At these low temperatures, any biological activity, including the biochemical reactions that would lead to cell death, is effectively stopped...

 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
Assisted reproductive technology
Assisted reproductive technology is a general term referring to methods used to achieve pregnancy by artificial or partially artificial means. It is reproductive technology used primarily in infertility treatments. Some forms of ART are also used in fertile couples for genetic reasons...

, 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
Conception device
A conception device is a medical device which is used to assist in the achievement of a pregnancy, often, but not always, by means other than sexual intercourse or NI...

 as a delivery system for the sperm.

Bad freezers

In 10–20% of all men, the semen doesn't 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.


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
Spermiogenesis is the final stage of spermatogenesis, which sees the maturation of spermatids into mature, motile spermatozoa. The spermatid is more or less circular cell containing a nucleus Golgi apparatus, centriole and mitochondria...



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 other words, older sperm are less likely to result in a successful pregnancy and, moreover, the cumulative fragmentation of sperm DNA over time makes it more likely that an older father will pass on achondroplasia
Achondroplasia dwarfism occurs as a sporadic mutation in approximately 85% of cases or may be inherited in an autosomal dominant genetic disorder that is a common cause of dwarfism...

 and possibly other genetic diseases. The onset of genetic deterioration of sperm is believed to have begun by the 24-28. For example, the percentage of sperm with highly damaged DNA, comet extent, DNA break number, and other comet measures has been found to be significantly higher in men aged 31–57 years than in those aged 20–30 years. 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, those whose fathers were 32 years or older had a risk of autism of 15.39 compared to those whose fathers were 25–29 years old.

Prospective fathers should take up age-related fertility issues with a qualified fertility specialist such as a reproductive endocrinologist.

Masturbation or intercourse

Sperm samples obtained via sexual intercourse
Sexual intercourse
Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which a male's penis enters a female's vagina for the purposes of sexual pleasure or reproduction. The entities may be of opposite sexes, or they may be hermaphroditic, as is the case with snails...

 contain 70-120% more sperm, with sperm having a slightly higher motility and slightly more normal morphology, compared with sperm samples obtained via masturbation
Masturbation refers to sexual stimulation of a person's own genitals, usually to the point of orgasm. The stimulation can be performed manually, by use of objects or tools, or by some combination of these methods. Masturbation is a common form of autoeroticism...

. Sexual intercourse also generates a 25–45% increase in ejaculate volume, mainly by increased prostate
The prostate is a compound tubuloalveolar exocrine gland of the male reproductive system in most mammals....


This intercourse advantage is even greater for men with oligospermia
Oligospermia, also oligozoospermia, refers 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...


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
Physical attractiveness
Physical attractiveness refers to a person's physical traits which are perceived to be aesthetically pleasing or beautiful. The term often implies sexual attractiveness or desirability, but can also be distinct from the two; for example, humans may regard the young as attractive for various...

 alone during stimulation, although there may be a slight correlation. Neither does any substantial fluctuations in sex hormones explain the intercourse advantage. It is hypothesized that sexual intercourse subdues an inhibition from the central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...

, but what, in turn, is the subduing factor is still not completely known.


Sperm are heat-sensitive, and cannot endure high temperatures. The body has compensatory mechanisms, like the cremaster muscle
Cremaster muscle
-Contraction:Its function is to raise and lower the testes in order to regulate the temperature of the testes and promote spermatogenesis. Contraction may also occur during arousal which can prevent injury to the testicles during sex....

 relaxing and letting the testicle
The testicle is the male gonad in animals. Like the ovaries to which they are homologous, testes are components of both the reproductive system and the endocrine system...

 hang further away from the warm body, sweating and a countercurrent exchange
Countercurrent exchange
Countercurrent exchange is a mechanism occurring in nature and mimicked in industry and engineering, in which there is a crossover of some property, usually heat or some component, between two flowing bodies flowing in opposite directions to each other. The flowing bodies can be liquids, gases, or...

 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
    A sauna is a small room or house designed as a place to experience dry or wet heat sessions, or an establishment with one or more of these and auxiliary facilities....

  • bathing
    Bathing is the washing or cleansing of the body in a fluid, usually water or an aqueous solution. It may be practised for personal hygiene, religious ritual or therapeutic purposes or as a recreational activity....

     for a long time in hot water
  • Long-time tanning bed sessions

Fever raises the body temperature, which can strike sperm quality.
In the same way, sperm quality can be lower in the summer.

Contrary to widely held beliefs, no evidence supports that wearing constrictive underwear, or "briefs," 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

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
In some male mammals the scrotum is a dual-chambered protuberance of skin and muscle containing the testicles and divided by a septum. It is an extension of the perineum, and is located between the penis and anus. In humans and some other mammals, the base of the scrotum becomes covered with curly...

, for example by the tunica vaginalis
Tunica vaginalis
The tunica vaginalis is the serous covering of the testis.It is a pouch of serous membrane, derived from the processus vaginalis of the peritoneum, which in the fetus preceded the descent of the testis from the abdomen into the scrotum....

, 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 partial or total inability to produce sperm in the affected testicle.


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.

Environmental chemicals

There has been evidence for a general decline in sperm counts in Europe and the USA between 1938 and 1990. While these dates were critiqued, further analysis supported the findings. A 2008 report demonstrates further evidence of the effects of feminizing chemicals on male development in each class of vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...

 species as a worldwide phenomenon; these chemical are suspected of reducing the sex ratio and sperm counts in humans. Ninety-nine percent of over 100,000 recently introduced chemicals are poorly regulated.

At least three types of synthetic toxins have been found in the semen of student volunteers: polychlorinated biphenyls (PCBs), DDT
DDT is one of the most well-known synthetic insecticides. It is a chemical with a long, unique, and controversial history....

, and hexachlorobenzene
Hexachlorobenzene, or perchlorobenzene, is a chlorocarbon with the molecular formula C6Cl6. It is a fungicide formerly used as a seed treatment, especially on wheat to control the fungal disease bunt...

. Leaks of dibromochloropropane (DBCP) have caused sterility in men. Soldiers that were exposed to dioxin during the Vietnam war have given rise to children with an increased rate of birth defects. Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...

, widely spread from nuclear weapon tests, accumulates in the testes, where it disrupts zinc metabolism, in turn causing genetic damage.

Phthalates , or phthalate esters, are esters of phthalic acid and are mainly used as plasticizers . They are used primarily to soften polyvinyl chloride...

, a ubiquitous pollutant, may cause decreased sperm production when having been exposed to it during prenatal development.


  • Depo-Provera, Adjudin
    Adjudin is a drug which is under development as a potential non-hormonal male contraceptive drug, which acts by blocking the production of sperm in the testes, but without affecting testosterone production...

    , and gossypol are examples of substances used as male contraceptive
    Male contraceptive
    Male contraceptives include condoms, withdrawal , and vasectomy. In other animals, castration is commonly used for contraception...

    s or in chemical castration
    Chemical castration
    Chemical castration is the administration of medication designed to reduce libido and sexual activity, usually in the hope of preventing rapists, child molesters and other sex offenders from repeating their crimes...

    . Recent studies have found that THC
    THC commonly refers to tetrahydrocannabinol, the main active chemical compound in Cannabis.THC may also refer to:* Tan Holdings Corporation...

     present in marijuana can confuse the movements of intact sperm, reducing their ability to achieve fertilization.

  • Selective serotonin reuptake inhibitor
    Selective serotonin reuptake inhibitor
    Selective serotonin re-uptake inhibitors or serotonin-specific reuptake inhibitor are a class of compounds typically used as antidepressants in the treatment of depression, anxiety disorders, and some personality disorders. The efficacy of SSRIs is disputed...

    s (SSRI) may cause low sperm count.

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


  • Anabolic steroid
    Anabolic steroid
    Anabolic steroids, technically known as anabolic-androgen steroids or colloquially simply as "steroids", are drugs that mimic the effects of testosterone and dihydrotestosterone in the body. They increase protein synthesis within cells, which results in the buildup of cellular tissue ,...

    s use and use of other hormones can reduce sperm quality. Changes in hormone homeostasis
    Homeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature or pH...

     affect the spermatogenesis
    Spermatogenesis is the process by which male primary germ cells undergo division, and produce a number of cells termed spermatogonia, from which the primary spermatocytes are derived. Each primary spermatocyte divides into two secondary spermatocytes, and each secondary spermatocyte into two...


The body also has natural variations in hormone concentrations, giving sperm quality natural fluctuations as well.


  • Coffee and alcohol lowers the sperm quality. However, the influence is probably minor.

  • Drinking over 1 liter of cola a day can decrease sperm quality by up to 30% (study claims there is correlation, but not causation)

  • Soy products decrease sperm quality due to the high content of a type of phytoestrogen called isoflavone
    Isoflavones comprise a class of organic compounds, often naturally occurring, related to the isoflavonoids. Many act as phytoestrogens in mammals...

    s. 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. 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.

  • A review in 2010 concluded that there is little evidence for a relationship with semen parameters and increased BMI.

  • Folate (vitamin B9) may protect sperm cells from aneuploidy
    Aneuploidy is an abnormal number of chromosomes, and is a type of chromosome abnormality. An extra or missing chromosome is a common cause of genetic disorders . Some cancer cells also have abnormal numbers of chromosomes. Aneuploidy occurs during cell division when the chromosomes do not separate...


Other chemicals

  • Gossypol
    Gossypol is a natural phenol derived from the cotton plant . Gossypol is a phenolic aldehyde that permeates cells and acts as an inhibitor for several dehydrogenase enzymes. It is a yellow pigment....

     present in crude cottonseed oil
    Cottonseed oil
    Cottonseed oil is a cooking oil extracted from the seeds of cotton plant of various species, mainly Gossypium hirsutum and Gossypium herbaceum...

     (and potentially the organ meats from animals poisoned with it) has been associated with reduced sperm production. Misuse of anabolic steroids can cause testicular atrophy
    Testicular atrophy
    Testicular atrophy is a medical condition in which the male reproductive organs diminish in size and may be accompanied by loss of function. This does not refer to temporary changes, such as those brought on by cold.Some medications can cause testicular atrophy...

     and reduced fertility.

Last ejaculation

How long the man has abstained
Sexual abstinence
Sexual abstinence is the practice of refraining from some or all aspects of sexual activity for medical, psychological, legal, social, philosophical or religious reasons.Common reasons for practicing sexual abstinence include:*poor health - medical celibacy...

 prior to providing a semen sample correlates with the results of semen analysis
Semen analysis
A semen analysis evaluates certain characteristics of a male's semen and the sperm contained in the semen. It may be done while investigating a couple's infertility or after a vasectomy to verify that the procedure was successful. It is also used for testing donors for sperm donation, in stud...

 and also with success rates in assisted reproductive technology
Assisted reproductive technology
Assisted reproductive technology is a general term referring to methods used to achieve pregnancy by artificial or partially artificial means. It is reproductive technology used primarily in infertility treatments. Some forms of ART are also used in fertile couples for genetic reasons...


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%.

  • 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
    Artificial insemination
    Artificial insemination, or AI, is the process by which sperm is placed into the reproductive tract of a female for the purpose of impregnating the female by using means other than sexual intercourse or natural 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. This increase in pregnancy rate occurs despite a lower value of total motile spermatozoa. 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.


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

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. 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
Room temperature
-Comfort levels:The American Society of Heating, Refrigerating and Air-Conditioning Engineers has listings for suggested temperatures and air flow rates in different types of buildings and different environmental circumstances. For example, a single office in a building has an occupancy ratio per...


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

In female

The environment in the uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...

 and fallopian tube
Fallopian tube
The Fallopian tubes, also known as oviducts, uterine tubes, and salpinges are two very fine tubes lined with ciliated epithelia, leading from the ovaries of female mammals into the uterus, via the utero-tubal junction...

s are advantageous. A pregnancy resulting from sperm life of eight days has been documented.

Home or in clinic

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

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.

In an in vitro study, sperm samples (in a petri dish) exposed to radio frequency
Radio frequency
Radio frequency is a rate of oscillation in the range of about 3 kHz to 300 GHz, which corresponds to the frequency of radio waves, and the alternating currents which carry radio signals...

 electromagnetic waves (as in mobile phones) showed significantly decreased sperm motility and viability, increased ROS
Reactive oxygen species
Reactive oxygen species are chemically reactive molecules containing oxygen. Examples include oxygen ions and peroxides. Reactive oxygen species are highly reactive due to the presence of unpaired valence shell electrons....

 level, and decreased ROS-TAC score.


Tobacco smoking
Tobacco smoking
Tobacco smoking is the practice where tobacco is burned and the resulting smoke is inhaled. The practice may have begun as early as 5000–3000 BCE. Tobacco was introduced to Eurasia in the late 16th century where it followed common trade routes...

 lowers the sperm quality, perhaps by decreased ability to attach to hyaluronan
Hyaluronan is an anionic, nonsulfated glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues...

 on the egg cell. However, the influence is probably minor. Smoking marijuana can decrease sperm quantity.

Long-term stress
Stress (medicine)
Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...

 is also suggested.

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."

Regarding diet, malnutrition
Malnutrition is the condition that results from taking an unbalanced diet in which certain nutrients are lacking, in excess , or in the wrong proportions....

 or an unhealthy diet
Healthy diet
A healthy diet is one that helps maintain or improve general health. It is important for lowering many chronic health risks, such as obesity, heart disease, diabetes, hypertension and cancer. A healthy diet involves consuming appropriate amounts of all essential nutrients and an adequate amount of...

 can lead to e.g. Zinc deficiency
Zinc deficiency
Zinc deficiency is insufficient zinc to meet the needs of biological organisms. It can occur in both plants and animals. Zinc deficient soil is soil in which there is insufficient zinc to allow plants to grow normally.-Description:...

, lowering sperm quality.

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

Lack of exercise, as well as excessive exercise, are minor factors. In professional sports
Professional sports
Professional sports, as opposed to amateur sports, are sports in which athletes receive payment for their performance. Professional athleticism has come to the fore through a combination of developments. Mass media and increased leisure have brought larger audiences, so that sports organizations...

, semen quality parameters tend to decrease as training requirements increase. The effect differs substantially between different professional sport types. For example, water polo
Water polo
Water polo is a team water sport. The playing team consists of six field players and one goalkeeper. The winner of the game is the team that scores more goals. Game play involves swimming, treading water , players passing the ball while being defended by opponents, and scoring by throwing into a...

 appears substantially less harmful to semen quality than triathlon
A triathlon is a multi-sport event involving the completion of three continuous and sequential endurance events. While many variations of the sport exist, triathlon, in its most popular form, involves swimming, cycling, and running in immediate succession over various distances...


A longer duration of sexual stimulation before ejaculation slightly increases sperm quality.

During the three decades leading up to the early 1990s, several studies suggested a population-wide decline in the quality of semen over the past 50 years. Definitive evidence for decreasing semen quality was lacking until a 1996 study published in the New England Journal of Medicine concluded that from 1973 to 1992 "each successive calendar year of birth accounted for 2.6 percent of the yearly decline in the sperm concentration, for 0.3 percent of the yearly declines in the percentages of motile, and 0.7 percent of the yearly declines in the percentages of normal spermatozoa (all P<0.001)".

Males carrying Robertsonian translocation
Robertsonian translocation
Robertsonian translocation is a common form of chromosomal rearrangement that in humans occurs in the five acrocentric chromosome pairs, namely 13, 14, 15, 21, and 22. Other translocations occur but do not lead to a viable fetus. They are named after the American biologist William Rees Brebner...

s in their chromosomes have significantly higher degree of sperm cell apoptosis
Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...

and lower concentration. Sperm cells also have decreased forward motility, but normal morphology.
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