Before revision: Thermal male contraception Prolonged testicular heating has been shown to reduce sperm counts , but no modern clinical trials have demonstrated the safety, contraceptive effectiveness, or reversibility of this approach.
After revision: Thermal male contraception Prolonged testicular heating had been shown to reduce sperm counts in 1941, considered as a method of birth control after 1968 and in the 1980s No modern clinical trials have demonstrated the safety, contraceptive effectiveness, or reversibility of this approach.