I reckon that if this ultrasound method - which is only in the early stages of research - turns out to be safe, reliable and easily reversible, it could become a popular option for men in long-term relationships. It's time that responsibility for birth control was shared equally between women and men - and not just for women's benefit. Men would rest easier at night knowing there will be no surprise bills from the Child Support Agency.

What's the hold-up?

Believe it or not, birth control methods for men have been researched for decades. I was involved in clinical trials in the 1970s but the pill I was working on made the whites of volunteers' eyes go pink so we abandoned it. Slow progress is partly due to a lack of funding as it's more challenging to find a male contraceptive that works. While women make one egg a month, men produce about 1,000 sperm every second.

But, 50 years after the advent of the female Pill, recent progress suggests that a hormonal method may be available within five years. Here are some promising developments: The ultrasound technique Scientists at the University of North Carolina hope to extend trials of pilot studies on rats to humans next year. Researchers are using ultrasound waves to deplete developing sperm cells in the testes (the male sex glands).

It doesn't involve surgery, needles or hormones, nor does it interfere with the mechanics of sex. A single 10 to 15-minute session every six months may be all that's needed. The instruments used are the same as those already used in ultrasound treatments for sports injuries. Apart from the need to keep a six-monthly appointment, we don't know of any downsides yet. If all goes well, it will be several years before the treatment is available. For more info, visit www.ultrasoundformen.org.

Hormone treatments
THE JAB - This is the most likely method to hit the market first, possibly within the next five years. Last year research published on more than 1,000 healthy, fertile Chinese men, aged between 20 and 45, claimed a success rate of more than 95%. Over two years, the men had testosterone injections every eight weeks and all their fertility levels went back to normal afterwards, apart from in two cases.

The World Health Organization and National Institutes of Health are supporting more trials around the world, which will conclude next year. Every couple of months, the men go to their GP for an injection containing a combination of testosterone and progesterone, which tricks the brain into shutting off sperm production.

A GEL - The Los Angeles Biomedical Research Institute has been recruiting men aged 18 to 50 to test treatment using two hormonal gels. Applied to the skin on the arm and abdomen, the hormonal combination should suppress sperm production for as long as it's used.

OTHERS - Other hormonal methods under research include an implant, patch or daily pill. The contraceptive effects are reversed within four to six months. So far, possible side effects of all hormonal methods may include changes to mood and sex drive, weight gain, hot flushes and acne but researchers hope to eliminate or minimise these.

However, hormonal methods probably won't be suitable for all men as they can cause a drop in good cholesterol. More research is needed to determine long-term safety on the heart and possibly the prostate. Also, hormonal treatments don't adequately suppress sperm production in some men.

Will men go for it?

Research by the FPA (family planning association) indicates a third of men would consider male contraception. But I recognise that, for any male contraceptive to catch on, men need to be reassured beyond doubt that their sex drive will remain intact and their long-term fertility will be unaffected once it is stopped. It's likely to attract men in long-term, trusting relationships. As far as casual sex is concerned, these methods don't protect against sexually transmitted infections.

Also in the pipeline: RISUG - Reversible Inhibition of Sperm Under Guidance (RISUG) involves injecting a synthetic gel into the vas deferens, the tubes through which sperm travels out of the body. The gel coats the lining of the vas deferens, partially blocking it and killing any sperm that pass. It would be a 15-minute outpatient procedure and could be removed whenever the man wants, using another injection to flush it out. Trials will take several years to complete.

So far research suggests it could be safe, effective, inexpensive and work for years after a single dose - and side-effects are just a slight, pain-free swelling. More research needs to be done on reversal though.

Additional research: Madeleine Bailey

Pic: Dominik Gwarek