An alternative

male contraceptive Male contraceptives, also known as male birth control, are methods of preventing pregnancy that solely involve the male physiology. The most common kinds of male contraception include condoms, outercourse, and vasectomy. In domestic animals, cas ...

method involves

heating A central heating system provides warmth to a number of spaces within a building from one main source of heat. It is a component of heating, ventilation, and air conditioning (short: HVAC) systems, which can both cool and warm interior spaces. ...

the

testicle A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testostero ...

s so that they cannot produce sperm. Sperm are best produced at a temperature slightly below body temperature. The muscles around a male's

scrotum The scrotum or scrotal sac is an anatomical male reproductive structure located at the base of the penis that consists of a suspended dual-chambered sac of skin and smooth muscle. It is present in most terrestrial male mammals. The scrotum cont ...

involuntarily tighten if the man's body temperature drops, and they loosen, allowing the testes to hang, if the body temperature rises. This is the body's way of keeping the sperm at an ideal temperature. This means that sperm production can be disrupted with increased temperature. Some suggest exposure to high temperatures (116 °F equal to 47 °C) can affect infertility for months. Male thermal contraceptive methods (MTC) derive their effectiveness from the alteration of the thermoregulatory function of the

.�
Contraceptions masculines non déférentielles : revue de la littérature
on www.urofrance.org (consulted on 19 March 2018). When this function is altered – by wearing tight underwear, being exposed to a high outside temperature, or by developing a fever, fertility may be impaired. Methods used include hot water applied to the

, heat generated by

ultrasound Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...

, and artificial

cryptorchidism Cryptorchidism, also known as undescended testis, is the failure of one or both testes to descend into the scrotum. The word is from Greek () 'hidden' and () 'testicle'. It is the most common birth defect of the male genital tract. About 3% of ...

(holding the testicles inside the abdomen) using specialized

briefs Briefs (or a brief) are a type of short, form-fitting Undergarment, underwear and swimsuit, swimwear, as opposed to styles where material extends down the thighs. Briefs have various different styles, usually with a waistband attached to fabric ...

. One of the initial experiments resulted in partial infertility lasting more than four years. Initial experiments suggest it is effective and safe, though there have not been long-term studies to determine if it has any

side effects In medicine, a side effect is an effect, whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse effects, it can also apply to beneficial, but unintended, consequence ...

on the body after reversal.

History

The deleterious effect of

hyperthermia Hyperthermia, also known simply as overheating, is a condition in which an individual's body temperature is elevated beyond normal due to failed thermoregulation. The person's body produces or absorbs more heat than it dissipates. When extreme ...

on male

fertility Fertility is the capability to produce offspring through reproduction following the onset of sexual maturity. The fertility rate is the average number of children born by a female during her lifetime and is quantified demographically. Fertili ...

has been known since ancient times. But it is from the 19th century onwards that the scientific community started to carry out research to better understand the phenomenon. In the 1930s, physician Marthe Voegeli explored the role of heat in male sterilization. She conducted experiments on the relationship between heat and

spermatogenesis Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubule ...

. She found that exposing the testicles to high temperatures in hot baths altered fertility. Sperm concentrations in the volunteers decreased so much so that they were considered

infertile Infertility is the inability of a person, animal or plant to reproduce by natural means. It is usually not the natural state of a healthy adult, except notably among certain eusocial species (mostly haplodiploid insects). It is the normal state ...

. She was the first scientist to popularize this alternative method of

contraception Birth control, also known as contraception, anticonception, and fertility control, is the use of methods or devices to prevent unwanted pregnancy. Birth control has been used since ancient times, but effective and safe methods of birth contr ...

for men. The thermal dependence of spermatogenesis was confirmed in various studies carried out between 1950 and 1970 by Doctors Watanabe and Robinson.Watanabe A. The effect of heat on human spermatogenesis. Kyushu J Med Sci.1959;10:101–117.Rock J, Robinson D. ''Effect of induced intrascrotal hyperthermia on testicular function in man''. Am J Obstet Gynec. 1965;93:793–801. The effect of temperature was first studied with external processes such as hot baths or saunas with temperatures above 40 °C over short periods of exposure.Robert S. Hotchkiss et John Macleod, "The effect of hyperpyrexia upon spermatozoa counts in men", Endocrinology, vol. 28, no 5, 1er mai 1941, p. 780–784 (ISSN 0013-7227, DOI 10.1210/endo-28-5-780
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/nowiki> consulted on 22 February 2019).Brown-Woodman PDC, Post EJ, Gasc GC, White IG. ''The effect of a single sauna exposure on spermatozoa''. Arch Androl. 1984;12:9–15. A history of testicular descent problems (

) or professional practices that lead to elevated scrotal temperature and even

fever Fever, also referred to as pyrexia, is defined as having a body temperature, temperature above the human body temperature, normal range due to an increase in the body's temperature Human body temperature#Fever, set point. There is not a single ...

are identified as factors that are prone to reduce fertility. Studies have been carried out with daily exposure of the testicles to less intense heat, around 37 °C, a temperature that is close to that of the body.Wang C, McDonald V, Leung A, Superlano L, Berman N, Hull L, ''et al.'' ''Effect of increased scrotal temperature on sperm production in normal men''. Fertil Steril. 1997;68(2):334–339. A contraceptive device using body heat was patented by Schopp Andreas in 1999.

How it works

The production of sperm can be disrupted with a rise in temperature.F. R. Kandeel et Swerdloff R. S.,"Role of temperature in regulation of spermatogenesis and the use of heating as a method for contraception", ''Fertil Steril'', vol. 49, no 1, janvier 1988, p. 1–23 (

PMID PubMed is a free search engine accessing primarily the MEDLINE database of references and abstracts on life sciences and biomedical topics. The United States National Library of Medicine (NLM) at the National Institutes of Health maintain the ...

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. Thermal methods involve heating the

s so that

sperm production Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubules ...

is slowed down. The spermatozoa are thus produced at a slightly lower temperature than that of the body, 1 to 2 °C below 37 °C. The

cremaster muscle The cremaster muscle is a paired structure made of thin layers of striated and smooth muscle that covers the testis and the spermatic cord in human males. It consists of the lateral and medial parts. Cremaster is an involuntary muscle, responsibl ...

covers the testicles. It works involuntarily. Its role is to bring the testicles down if the body temperature rises or to raise them if the body temperature drops. This process allows it to regulate the temperature of the testicles and to keep it several degrees lower than that of the body in order to enable an ideal spermatogenesis.R. Mieusset, « Cryptorchidie et température testiculaire », Andrologie, 1995, p. 317-325
read_online_[archive
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/nowiki>. Other effects have also been observed, such as a decrease in motility and an alteration in the morphological characteristics of the spermatozoa that are produced.Mieusset R, Bujan L, Mansat A, Pontonnier F, Grandjean H. ''Hyperthermia and human spermatogenesis: enhancement of the inhibitory effect obtained by 'artificial cryptorchidism. Int J Androl. 1987;10:571–580.Shafik A. ''Testicular suspension as a method of male contraception: technique and results''. Adv Contr Deliv Syst. 1991;VII:269–279. Some suggest that exposure to high temperatures (47 °C) can affect fertility for months.

Efficiency

Thermal methods do not cause azoospermia, but a reduction of the Spermatozoon, spermatozoa below the contraceptive threshold considered to be effective. This contraceptive threshold was defined in 2007 for male thermal, chemical and hormonal contraception methods. It corresponds to 1 million spermatozoa per milliliter per ejaculate.Jean-Claude Soufir, "Hormonal, chemical and thermal inhibition of spermatogenesis: contribution of French teams to international data with the aim of developing male contraception in France", Basic and Clinical Andrology, vol. 27, 13 janvier 2017, p. 3 (

ISSN An International Standard Serial Number (ISSN) is an eight-digit serial number used to uniquely identify a serial publication, such as a magazine. The ISSN is especially helpful in distinguishing between serials with the same title. ISSNs ...

br>2051-4190
DOIbr>10.1186/s12610-016-0047-2read online [archive]
consulted on 19 March 2018) The only method that has been tested on enough volunteers to establish that the effectiveness of thermal male contraception is satisfactory is the

artificial cryptorchidism Artificiality (the state of being artificial or manmade) is the state of being the product of intentional human manufacture, rather than occurring naturally through processes not involving or requiring human activity. Connotations Artificiality ...

method with testicular ascent using a specific device. During the clinical studies, 50 couples were followed over 537 cycles of pregnancy. Only one resulted in a pregnancy due to a misuse of the technique. The

Pearl Index The Pearl Index, also called the Pearl rate, is the most common technique used in clinical trials for reporting the effectiveness of a birth control method. It is a very approximate measure of the number of unintended pregnancies in 100 woman-years ...

would therefore be less than 0.5 and this contraception method can be considered effective according to the standards of the World Health Organisation (WHO).

Adverse effects

The maximum limit of exposure to heat is around 45 °C, which causes the coagulation of intracellular proteins on living cells. However, exposure above 41 °C for short periods of time may be used, as has been the case for scientific studies on the effect of hot baths. In the case of

or thermal insulation of the testicles, the use of a temperature close to that of the body (37 °C) has made it possible to increase the time of exposure in order to slow down the spermatogenesis process over longer periods, 4 years in a row at most. To date, only a decrease in testicular volume by a few percents has been observed during the contraceptive period. There is no evidence of an increased risk of testicular torsion. However, it has been shown that the nuclear quality of the spermatozoa was altered during the phase of inhibition of the spermatogenesis, but that this was reversible 3 months after the subject stops practicing artificial cryptorchidism.Ahmad G, Moinard N, Lamare C, Mieusset R, Bujan L. ''Mild testicular and epididymal hyperthermia alters sperm chromatin integrity in men''. Fertil Steril. 2012;97:546–553. This finding should be taken into account when using this contraception method, during the inhibition phase and for 3 months after treatment discontinuation.

Methods

Hot baths

Within a few months of daily exposure, the number of spermatozoa drops provided the temperature is higher than that of the body: 38 to 46 °C instead of 37 °C.

Artificial cryptorchidism

The principle of

or male thermal contraception with testicle lifting is simple. Warming the testicles with body heat by keeping them in the inguinal sack for several hours a day reduces sperm production below the contraceptive threshold of 1 million/ml.SHAFIK A. : ''Contraceptive efficacy of polyester-induced azoospermia in normal men''. Contraception, 1992 ; 45 : 439-451. Knowledge of the thermal dependence of spermatogenesis dates back to 1941. However, it was not until 50 years later, in 1991, that the first study reporting the contraceptive effect of heat on men was published: andrologists Roger Mieusset and Jean-Claude Soufir were the first to get results with the artificial cryptorchidism method (testicles held inside the inguinal sack) with the use of suited devices.

Thermal insulation of the testis

A surgical intervention causes the testicles to be held in the inguinal sack.

Heating devices

Wearing a device that presses the man's testicles against his body on a daily basis can raise their temperature by 2 °C and thus slow down sperm production.Charlotte Anglade
« Contraception masculine : Erwan, 38 ans, porte-étendard du "slip chauffant" »
rchive on ''lci.fr'', 26 September 2019 (consulted on 24 May 2020). To be effective, the device must be worn daily (approximately 15 hours per day) for at least 3 months, which is equivalent to the sperm's life cycle. This allows the contraceptive threshold of one million per millilitre of sperm to be temporarily reached (compared to an average of 15 to 60 million).Juliette Pitisci
« Contraception masculine : connaissez-vous le slip chauffant ? »
rchive on ''rtbf.be'', 18 January 2020 (consulted on 24 May 2020). Practitioners should do pre- and post-usage testing to check their sperm counts. Various techniques are considered, such as an insulating bag with heating elements in contact with the scrotum.

Heating underwear

The heating briefs are one of the available devices. This method was invented and is prescribed by Doctor Mieusset at the University Hospital of Toulouse.Louise Pluyaud,
La contraception, c'est aussi une histoire d'hommes
rchive on ''TV5MONDE'', 2 October 2015 (consulted on 1 June 2020) In 2019, a French news channel reported that "only about twenty men were wearing this contraceptive garment in France". It is not sold on the market and a poorly handcrafted design can cause discomfort or irritation. Other "do-it-yourself" models called "jock-strap" or "bra" also exist.Association pour la recherche et le développement de la contraception masculine, �
Méthode thermique
» rchive(consulted on 24 January 2021)

Silicone ring

Another available device is the silicone ring. Invented and patented by Maxime Labrit, a French nurse, it is available for purchase on the Internet for a few dozen euros.

Ultrasounds

One method under investigation is ultrasound, which involves the application of high-frequency sound waves to animal tissue, which in turn absorb the sound waves' energy as heat. The possibility for ultrasound's use for contraception is based on the idea that briefly heating the testes can halt sperm production, leading to temporary infertility for about six months. Additionally, ultrasound could affect cells' absorption rates of ions, which itself could create an environment unfavorable to

. Its extremely localized effects on animal tissues make ultrasound an attractive candidate for research, but so far studies have only been performed on non-human animals, such as dogs.

Notes and references

External links

* From linked International Male Contraception Coalition and Male Contraception Information Project: ** ** ** * a toxicologist's account of successful experiments on himself with suspensory briefs, also provide
excerpts from some research papers
* {{cite news , last=Asaravala , first=A , title=Laptops a Hot Fertility Issue , url=https://www.wired.com/news/medtech/0,1286,65970,00.html , date=2004-12-04 , publisher=Wired Contraception for males Experimental methods of birth control