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An experimental male contraceptive method involves heating the testicles so that they cannot produce sperm. Sperm are best produced at a temperature slightly below body temperature. The muscles around a male's scrotum 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. Although research has not addressed methods of applying heat, 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.
Methods used include hot water applied to the scrotum, heat generated by ultrasound, and artificial cryptorchidism (holding the testicles inside the abdomen) using specialized briefs. 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 on the body after reversal. The optimal heat level and time period of exposure are not known.
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 spermatogenesis. 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.
- From linked International Male Contraception Coalition and Male Contraception Information Project:
- "External heat". International Male Contraception Coalition. Retrieved 2008-06-21.
- "Suspensories / Internal heat". International Male Contraception Coalition. Retrieved 2008-06-21.
- "Heat Methods of Male Contraception". Frontiers in nonhormonal male contraception. Male Contraception Information Project. Retrieved 2008-06-21.
- Jenks, C (2006). "Experimental Method of Male Contraception". Retrieved 2008-06-21. – a toxicologist's account of successful experiments on himself with suspensory briefs, also provides excerpts from some research papers
- Asaravala, A (2004-12-04). "Laptops a Hot Fertility Issue". Wired.
- Kandeel, F. R.; Swerdloff R. S. (Jan 1988). "Role of temperature in regulation of spermatogenesis and the use of heating as a method for contraception". Fertil Steril. 49 (1): 1–23. PMID 3275550.
- Voegeli, Martha M.D. "Data on the thermic method for temporary male sterilization (1954)". Retrieved 14 January 2012.
- "Heat Methods". International Male Contraception Coalition. Retrieved 2015-02-17.
- "Expanding Options for Male Contraception". Planned Parenthood Advocates of Arizona. 2011-08-08. Retrieved 2012-03-28.