Most male hormonal contraceptives being developed include some combination of progestin and an androgen. These two hormones work together to block the signal that initiates sperm production, similar to how birth control pills prevent the release of an egg in women.
But male contraception doesn't seem like it will be as simple as popping a pill everyday.
Dr. Peter Liu, one of the study authors, believes that the male hormonal contraception method with the most potential will combine a monthly injection of an androgen, like testosterone, with either an implanted, long-lasting capsule of progestin or a daily pill of the same hormone. It is also important to note that hormonal methods of contraception do not protect against sexually transmitted diseases.
The side effects of this type of contraception would be minor: pain or some bruising at the site of injection. Some men who have tried similar methods in trials have complained that the treatment increases acne. However, no long-term studies have yet been completed, and Liu suggests that studies on prostate and cardiovascular disease will have to be done once these drugs are available.
As for the popularity of male contraception, Liu is optimistic that men will want to take an active role once this method is available.
"Couples want to share the responsibility of family planning, and this allows them to do so," says Liu.