The potential of mild testicular heating as a safe, effective and reversible contraceptive method for men

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Abstract
A preliminary assessment of the contraceptive efficacy of a daily mild increase (1-2 degrees C) in testicular temperature during waking hours is reported in nine couples using two techniques of non-surgical fixation of the testes close to the inguinal canal. With technique 1, immobilization was achieved by passing the penis and the empty scrotum through a hole made in close-fitting underwear; there was one pregnancy, from a man who stopped the heating after 7 weeks, for 42 cycles of exposure in three couples. With technique 2, immobilization was achieved by adding a ring of soft material surrounding the hole in the underwear; there was no pregnancy for 117 cycles of exposure in six couples. Reversibility and safety were assessed. These preliminary results suggest that a daily mild increase in testicular temperature could be a potential contraceptive method for men.Among normal fertile men, induced elevation of body temperature or scrotal temperature has been reported to decrease the level of sperm output and motility. The heating of testes was therefore suggested as a potential contraceptive method for men as early as 1959. In most studies, however, the temperature elevation was large, lasted a short time, and required an impractical heat source. Robinson and Rock in their 1967 study suggested that a rise of one degree Celsius in scrotal temperature with daily scrotal insulation during waking hours would be sufficient to confer contraception. This paper reports the preliminary assessment of the contraceptive efficacy of a daily mild increase in testicular temperature during waking hours in nine couples. The men were aged 23-34 years of mean age 29.9. All had baseline semen parameters within the normal range as defined by the World Health Organization. An assumed one-two degree Celsius increase in testicular temperature was achieved by lifting and fixing the testes close to the inguinal canal using either of two nonsurgical methods. Once lifted next to the inguinal canal, the testes of three subjects were immobilized out of the scrotum on a daily, waking-hour basis by passing the penis and empty scrotum through a hole made in close-fitting underwear. Among 42 cycles of exposure in the couples, the only pregnancy was induced by a man who stopped the heating after seven weeks. The menstrual cycle was considered an exposure cycle. The testes of the other six men were secured by passing the penis through the hole in underwear which had been surrounded by a ring of soft rubber. No pregnancy occurred among these men for 117 cycles of exposure. No modifications appeared among subjects during clinical examinations, with libido and sexual rhythm remaining unaffected. Recovery of sperm number and motility occurred within 12-18 months for all subjects. All of the men using the former of the two techniques to secure their testes have fathered children since the end of testicular heating, while none of the other six men have yet attempted to impregnate a female. These results point to the potential applicability of this male contraceptive method among the general public.