Researchers think they may be a step closer to a male birth control pill after a single-dose contraceptive temporarily “stopped sperm in its tracks” in mice.

The newly developed drug suppresses sperm motility (the ability for sperm to move) in mice, according to a study published in Nature Communications today.

A single dose of the drug was found to be 100% effective in preventing pregnancy for the first two hours in mice, and 91% effective for the first three hours. 

The drug didn’t affect the mice’s normal mating behaviour and their fertility levels returned to normal after 24 hours.

The mice suffered no negative effects when the drug was given to them continuously for six weeks. 

Researchers Jochen Buck and Lonny Levin at Weill Cornell Medicine say the results could be a “game-changer” in developing the male birth control pill, a task that’s proven difficult so far. 

They say more research is needed to see whether the drugs are as effective in humans without side effects. 

They say other attempts to develop male contraceptives have been limited by low efficacy, long pre-treatment times, or negative side effects.

While other experimental male contraceptives can take weeks to work, and then weeks again to wear off, Buck and Levin say the sperm inhibitor they have developed works within 30 minutes to an hour. 

Its effects also wear off within hours, meaning men could potentially take the drug only as and when they need it.

At the moment, contraceptives for people with penises are limited to condoms (effective if people use them correctly every time) and vasectomies (which can be reversed but are usually seen as a permanent option).

Sharing the load

There would definitely be a demand for a male birth control pill if one is ever successfully developed, according to New Zealand Family Planning chief executive Jackie Edmond. 

“It’s always great to have more options,” she says.

“We know that women currently take the lion’s share of responsibility for contraception, and for men to have another option for contraception would [mean] sharing that load a bit further.”

Edmond says it’s great to have research into a male birth control pill as men also want to protect against unplanned pregnancy.

She says it’s been a struggle to get this sort of contraception across the line before, especially given previous trials involved treatments that took a long time to work.

“This [new drug] looks a bit more immediate … which looks promising,” she says. “But we’ll wait and see whether it makes it to the market.”

Edmond says men looking to protect against unplanned pregnancy in the meantime should talk to their partner.

“Make sure that you’re at least sharing the conversation around contraception,” she says.

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