Though trials for a potentially breakthrough treatment have been encouraging, widespread uptake remains some way off.

It’s for women like me, who suffer negative side effects (mine is migraines) when taking
the contraceptive pill, that Dr Diana Blithe, a clinical researcher in Maryland, United States, has spent the past decade developing a male contraceptive.

“It’s a female matter,” she explains. “Many have had bad experiences with whatever hormonal contraception products they’ve been using and they don’t want to take it. A male product makes the whole conversation surrounding contraception more balanced.”

Her potentially breakthrough invention is not a pill but a pump that delivers two teaspoon-sized doses of gel, which the man applies to his shoulders – literally shouldering the responsibility of birth control.

Trials show that the product can be effective in eight weeks, although Blithe, who is project lead on the National Institutes of Health’s Contraceptive Development Programme, suspects that sperm are suppressed more quickly. “I’m not usually a glass half-full person but I’m really excited; we didn’t expect the results to be as good as they are,” she says.

For women, it’s a big moment. Nearly half of all women who start taking the pill discontinue in the first year because of the side effects. I wonder how excited men will be by the prospect of hormonal contraception. I don’t think I’m alone in suspecting that if they were genuinely up for it, a male pill would have been invented long ago.

Tet Yap, a leading consultant andrological surgeon, admits his wife laughed when he told her about the new product. “As if men are going to take that!” she said.

Yet Yap insists men are more open-minded about taking a contraceptive product than we give them credit for; his male patients have already been asking about the new product, he says.

When I asked fathers at my children’s school if they’d take it, they all said they would, so long as it was safe and had no negative side effects (ha, I thought – try taking the female pill).

Yet a recent YouGov study suggests a third of sexually active British men would consider using hormonal contraception, the same as the percentage of British women who currently use such medication, while eight out of every 10 people in the survey viewed contraception as a shared responsibility.

“It’s a societal conversation,” Yap says. “The responsibility of the man has been ignored for a long time and if there was suddenly something available that was easy for them to take, it could spell a change in the way people view contraception.”

The reason there’s never been male contraception before, he says, is because it’s tricky to develop – men produce about 1000 sperm per second. For the past 50 years, scientists have been grappling with hormonal and non-hormonal approaches, most recently, a bi-monthly hormonal injection.

Research showed it was effective in 96 per cent of users but studies were terminated early in 2016 due to users experiencing serious negative side effects including mood swings, depression, irregular heartbeats and suicidal thoughts.

The latest innovation, called NES/T gel, contains Nesterone, a form of progestin, which blocks native testosterone from being produced and stops sperm production. It also has synthetic testosterone, to ensure there is the correct amount of testosterone available for the androgen-dependent functions of the body.

“You don’t want to stop sexual function, which is why we replace the testosterone,” Blithe says. Results show that the product reached low sperm levels in 80 per cent of men after just 12 weeks, although scientists believe the study may have missed key data between four and eight weeks, which could indicate that it’s even more effective.

So there’s no chance of men wriggling out by arguing male contraception doesn’t work as well as women’s. Scientists believe NES/T gel has a similar effectiveness to the female hormonal pill (8 per cent failure rate) but it could be that it’s even safer, Blithe says, particularly given that if a man accidentally misses one or two doses, it’s unlikely to lead to a pregnancy as it takes between eight and 10 weeks for sperm production to recover.

“Ovulation can happen very quickly if you miss one or two doses, whereas there aren’t sperm waiting to go,” she explains.

Still, will women feel able to put their trust in it? Fiona Kenner, a family planning adviser in Devon, Britain, believes that while women like the idea of contraception being a shared responsibility, many will ultimately decide to stick with their methods – no matter how much they trust their partner to use the gel properly – as neither method is foolproof and they’d rather be in control of the risks.

“At the end of the day, it’s my body that’ll get pregnant – my boyfriend is never going to be as careful as me,” she says.

The gel is also not safe for casual sex; unlike condoms, it does not offer protection against sexually-transmitted diseases. Blithe expects it to be used by couples rather than on the dating scene. “If you meet a guy in the bar and he says, ‘I’ve been taking contraception’, would you believe him? I wouldn’t,” she says.

There is a way of checking up on this, though, she continues, by using a sperm check kit available in pharmacies, although I can’t imagine many women are going to want to walk around with one of them in their handbag. The logistics of having to perform the test and wait 15 minutes for results would kill the moment somewhat and besides, Yap is quick to point out that these aren’t 100 per cent reliable.

Yet plenty of men are eager to get their name down for the next trial. Gerry Hale, whose wife Linda cannot take the contraceptive pill due to her migraines, says male contraception can’t come soon enough.

“I’m all for taking my share of the responsibility,” he says. Linda says she trusts Gerry to take it properly as neither of them wants another child. “If the effectiveness is genuinely the same or better than the pill, I’m all for it,” she says. “For us, this could be the perfect solution.”

Not all women are going to be so quick to hand over responsibility, though. Linda concedes it’s only because she knows Gerry so well that she’s prepared to entrust him with the responsibility – women aren’t going to take the subject of male contraception lightly, she says, given what it means for their body.

The men who have used the gel so far – about 300 of them – have not reported any serious side effects such as depression or suicidal thoughts. If anything, they’re reporting a slightly increased libido, which Blithe suspects is why many of them have asked to repeat the trial or continue taking the gel once their trial has ended.

“One man in our study reported that his girlfriend came off birth control, which had been suppressing her libido, at the same time – so they both enjoyed the experience of a slight increase,” she says.

While the libido factor will presumably be a big selling point, not all women like the thought of it. “It makes the gel a big no-no for me,” one friend told me. “Next thing I know, my boyfriend will be trying to overdose on it.” Yet Blithe does not expect the product to be abused in the same way as anabolic steroids, as the man would have to use up his whole supply and even then might not reach the desired levels.

There are other concerning factors for women, such as the fact they need to stay away from the gel as continuous exposure to testosterone can interfere with the menstrual cycle and cause excess facial hair and acne. Some male users have experienced acne on their shoulders. “If you’re going to have intimate contact right after applying it you need to wear a T-shirt, that way there’s no chance of transference,” explains Blithe, who carried out transference studies on the product.

More pressing than any of this, however, is whether the product actually does its job in preventing pregnancy. Yap says he wouldn’t use it himself or recommend it to his patients before larger and longer clinical trials have been completed. He’s concerned about the study’s threshold for sperm suppression, which was set at one million or fewer sperm per millilitre, which according to Blithe, is low enough to prevent conception (normal sperm counts can range from 15m to 200m per millilitre).

Yet Yap argues it only takes one surviving sperm for a woman to become pregnant. “With a vasectomy, we have to reach zero on the sperm count to conclude it was successful and even then there’s a 1 in 2000 failure rate,” he says.

He’d also like to see further studies in the reversibility of the product. The results so far suggest that couples have gone on to conceive successfully after stopping the gel, with no adverse effect on the child.

“The expectation is that men will recover and go on to have children,” Blithe says. “We think we’re just shutting their sperm production down and not doing permanent damage; we don’t expect there to be any residual problem.” She believes the technology used to create the gel could be used in creating groundbreaking female contraception.

“We’re developing it in a ring at the moment; when you remove the ring you have a bleed for a few days but you can control when that happens,” she says.

Drug production is a snail’s-pace game, though. Even if future clinical trials on NES/T gel are successful, men (and women) will have to wait at least eight years before it’s licensed. There is currently no path to approval in place for male contraception and no guidelines.

“It’ll be hard for regulatory agencies to assess as there is no specific benefit for the male body – they’re assuming the risk for something that is protecting someone else. It’s an unusual risk-benefit ratio,” Blithe explains.

Yap is certain that if it does make it into pharmacies, there will be men queuing to start taking it – they’ll have no choice; their female partners will be driving it.

“Male contraception will always be a female issue,” Blithe agrees.

“The anxiety women experience as their partner reaches the end of our trial and they have to go back to their own contraception method shows just how much it matters to them.”