If you're a heterosexual man in a long-term relationship but would rather not hear the patter of tiny feet just yet, would you willingly submit to a monthly contraceptive jab in the buttocks?
The front page of yesterday's Daily Express trumpeted the development of a "male pill" – a hormone injection that renders men temporarily infertile and is "as effective as the female pill in preventing pregnancy". The story reported a phase III clinical trial in China of a testosterone jab involving 1,045 fertile men which found that the treatment caused no significant side effects (apart from increased libido) and almost completely suppressed sperm production. Better still, the men got their fertility back when the injections were stopped.
What the story failed to mention was that out of 1,045 men recruited into the trial, only 733 completed the 30 monthly injections and follow-up. That's quite a high drop-out rate, but perhaps not all that surprising given that the men had to present themselves at a clinic every month and drop their trousers to receive the jab. It probably stung, just a bit. On top of that, it took several months after the injections began before the men could safely be considered infertile.
To monitor their declining sperm counts the men would also have had to submit regular semen samples.
Around 5% of the volunteers who made it to the end of the trial never achieved "azoospermia". In other words their partners continued to risk unwanted pregnancy, in the absence of another form of contraception. For them, it had all been a complete waste of time. All those indignities for nothing.
Two of the men failed to regain their full fertility when the injections were stopped. The injections may not have been to blame, but it might give a man pause for thought before embarking on such a course of contraception.
The development of a male version of the contraceptive pill is a noble goal, but hormone injections have severe practical and psychological drawbacks for men. In 2004 I wrote an article for New Scientist magazine detailing some of the alternatives to hormone injections. Some of them looked very promising. One of the principal advantages over using testosterone was that they targeted the later stages of sperm production, so their effect kicked in much more quickly.
Unfortunately they were all a long way from reaching the shelves of your local pharmacy, partly because major pharmaceutical companies – whose financial muscle would be essential to take them through hugely expensive clinical trials, without any guarantee of success – wouldn't touch them with a barge pole. Very little has changed in the past five years.
What's a guy to do? Amazingly, there did seem to be a highly effective, reversible form of male contraception on the brink of worldwide adoption. It was a type of vasectomy called RISUG (Reversible Inhibition of Sperm Under Guidance) involving the injection of a gel into the vas deferens. The gel sets to form a loose polymer that allows the passage of seminal fluid but knocks out sperm.
The procedure is fast, doesn't require general anaesthetic and apparently prevents conception for at least 10 years without further maintenance. The only reported side effect is a slight scrotal swelling and tenderness that resolves after a few weeks. Flushing the polymer out with sodium bicarbonate immediately restores fertility.
RISUG was invented by an Indian biomedical engineer, Sujoy Guha, and is undergoing phase III clinical trials in India. Its progress to market was delayed by years when the reliability of earlier toxicology tests in animals was called into question, but it looks as though it's back on track.
The development of a popular form of male contraception that rivals condoms for effectiveness would be a triumph for sexual equality. Whether it would match the effectiveness of condoms in preventing the spread of sexually transmitted infections like HIV is another question entirely.
