A male contraceptive pill prevents 100% of pregnancies, suggests new study, but will men actually take it?

Birth control is undergoing a revolution. In the coming years, it’s expected that a new male contraceptive will become available, easing the contraceptive burden that currently rests falls on women and people with uteruses. 

As it stands, the only available birth control options for cisgender men and people with penises are condoms and vasectomies, whereas cisgender women and people with uteruses can access the combined contraceptive pill, the mini pill, the implant, vaginal rings, the IUD coil, and the contraceptive injection. As such, the responsibility to use contraception – and its associated side effects – invariably lands on women. 

The good news? It’s looking likely that more male contraceptive options will soon hit the market. The not-so-good news? We don’t know if men will actually use them. Of course, everyone – whatever their gender – should be free to make informed decisions about their reproductive health. But it’s about time women stopped carrying the contraceptive burden alone. 

What is the male contraceptive? 

While it’s very much in the test phase, a new male contraceptive pill that’s been hailed as a ‘game-changer’ has been undergoing research as part of a US Government-funded study. And the results, revealed in February 2023, have been hugely promising. The drug is taken 30 minutes before sex and appears to be 100 per cent effective at stopping pregnancies for at least two hours. It works by halting men’s sperm swimming towards eggs, or maturing to the stage where it is able to fertilize an egg to create a baby.

The drug does so by targeting an enzyme – adenylyl cyclase (sAC), which gives sperm the ability to swim through the female reproductive tract and fertilize an egg.  The enzyme is naturally missing in a very small number of men who are infertile. This suggests healthy men given a drug to block the enzyme would be made temporarily infertile too.

The study was performed on groups of mice and scientists discovered that the drug eliminated the mice’s fertility in just 30 minutes. It did not interfere with their mating behaviour in other ways, though – the males still mated with females but no pregnancies occurred in this period of time. Sperm collected from the female mice remained debilitated. 

According to the study, contraceptive effectiveness was found to be at 100 percent in the first two hours and 91 percent in the first three hours. By 24 hours, it had returned to normal levels. Researchers found no negative health impacts when the drugs were continuously given to the mice for six weeks.

In the findings, which were published in Nature Communications, Dr Melanie Balbach, a postdoctoral associate, said: “Our inhibitor works within 30 minutes to an hour. Every other experimental hormonal or non-hormonal male contraceptive takes weeks to bring sperm count down or render them unable to fertilize eggs.”

She explained that since sAC inhibitors wear off within hours, and men would take it only when and as often as needed, they could allow men to make day-to-day decisions about their fertility.