Over half a century on from when the female birth control pill was first approved for wide scale use in the 1960s, efforts to produce a viable male equivalent appear to finally be reaching a long-awaited climax.

Last month a team of scientists at the University of Minnesota revealed that they had developed a male contraceptive pill that was shown to be highly effective after early-stage testing carried out in the laboratory.

According to the findings, which were presented at the American Chemical Society’s spring meeting, when given orally to male mice for four weeks, the pill “dramatically reduced” their sperm counts and was 99 percent effective in preventing pregnancy in their mates — without any observable side effects.

“This is long overdue,” says Md Abdullah al Noman, a PhD candidate and one of the project’s main researchers. “We’ve made a lot of progress in gender issues, but this field has been lagging behind for a long time. We hope our pill can change that. It could be the next big thing in birth control.”

The team said the mice were also able to father offspring again four to six weeks after they stopped receiving the treatment, giving hope of the pill being a reliable but, crucially, reversible option for male contraception.

Professor Richard Anderson, a leading expert in reproductive science at Edinburgh University, says that the new pill is “brilliant” in terms of its scientific approach.

The pill, which was produced after a research stage involving the synthesis of around 100 different alternative chemical compounds, works by blocking the user’s proteins from binding with vitamin A, which is important for fertility in mammals.

Researchers will begin testing human clinical trials by the end of the year, but with the caveat that there’s no guarantee these hugely promising results in mice will translate to humans. Expectations of an immediate impact would also be premature: it will have to receive FDA approval and won’t be available for human use for years.

But Anderson, who is developing a non-hormonal, “rub-in” male contraceptive gel that is already in its second phase of human trials, argues that the long-term answer to male birth control is likely to come through several methods. 

“One might imagine in time a variety of different methods: pills, gels and injections,” he says. “Increased choice will result in increased overall use.”

There are 12 categories of birth control. But currently men have only two effective options: male condoms and vasectomy. However, condoms are single-use and have a user failure rate of 18 percent, whereas vasectomies — a minor surgical procedure that prevents sperm from traveling into the ejaculate — are not considered to be reliably reversible.

But when it does arrive, a viable male contraceptive could have a massive impact. In the United States alone, 45 percent of pregnancies are unplanned. Globally, there are 121 million unintended pregnancies each year, according to the UN’s State of World Population 2022 report, over 60 percent of which end in abortion, mostly through unsafe procedures. Numerous studies have highlighted the negative consequences of the gender imbalance of contraception availability, including maternal and child deaths.

Critics say the belated arrival of a male pill — the female version emerged in the 1960s — and the limited overall efforts to develop male contraception is largely down to a highly gendered, systemic approach to reproductive health.

“One of the main drivers of this delay is that historically and culturally reproductive health has been the responsibility of a woman to control themselves, rather than a man controlling his fertility,” says Elinor Cleghorn, author of Unwell Women: A Journey Through Medicine And Myth in a Man-Made World. 

“Women’s fertility and sexuality is thought to be something controlled and managed. But when it comes to the side effects in men it’s seen as intolerable.”

In 2016, a 96 percent effective hormone-based, male contraception pill that blocked testosterone was found to have side effects, including weight gain, depression and lower sexual desire. But while those side effects closely correlate with female contraceptives that have long been on the market, that put an end to the product.

As Cleghorn discusses in her book, the female contraceptive pill in the US deployed in 1960 contained three times the levels of synthetic hormones than the modern version. She found that the side-effects, which included fatal blood clots, were deliberately downplayed and that it took a sustained feminist campaign to bring the issue to the attention of a congressional hearing in 1970. 

Christina Wang, an expert in contraceptives and male reproductive biology at The Lundquist Institute at Harbor-UCLA Medical Center, believes part of the delay in developing male contraception is also due to a lack of support from funding bodies.

“Research into male reproductive biology is so far behind gynecology,” says Wang, who in the 1980s was part of a World Health Organization task force to develop male contraception — until financial support stopped.

The new male pill, however, is expected to avoid some of those previous issues. Since it is a non-hormonal method, there should be fewer side effects.

Yet the big lingering question remains: will men actually take the pill? Several surveys suggest the majority would, including one published this month, which found that 58 percent of British men backed male contraception. 

A study by Global Market Insights in 2018 found that if a male contraceptive method were approved, the market could grow to around $1 billion in five years, and continue to grow at a rate of six percent over the next decade.

Professor Anderson points to further evidence that male partners are likely to be willing to use a contraceptive. “If you walk down the street and ask men if they have ever used a condom, the vast majority would say yes,” he says. “It’s simply a case of making it available and accessible over time.”

However, there may be more complicated factors underlying any future take-up of contraception by men. “Unplanned pregnancy has improved a lot, but it is very uneven across society,” says Wang. “Among the socially deprived and poor communities, it has not improved so much.”

Nonetheless, the consensus is that any new form of male contraception is likely to be a significant step forward for improving reproductive health equality.

“The male pill could democratize this field,” says Cleghorn. “We need to move away from these rigid, antiquated gender roles and from the idea that men’s sexuality and libido is something to be protected and for women it is a price to be paid.”