Sylvia Cormack's decision to go ahead with the public piercing of her nipples was met with barely repressed jubilation by a group of body-piercing enthusiasts gathered together at a conference in London.

As she lay on the floor, head in her lover's lap, nipples firmly clamped, I felt as though I had stumbled into some ancient initiation ceremony. The atmosphere was one of warm camaraderie and the completed procedure, which took no more than three minutes, was met with cheers and congratulations from the audience.

Body piercing provokes an instinctive shudder in many people because it touches on the taboos surrounding sexuality, blood and pain. But like tattooing, which has also seen a resurgence, body piercing is as old as civilisation.

Navel piercing was a status symbol to the ancient Egyptians, while nipple rings were the emblem of Roman centurions, both as a mark of courage and, it is claimed, a practical way of keeping their tunics up. Some Victorian gentlemen favoured a foreskin ring nicknamed the 'Prince Albert' which was used to anchor their genitals inside the skin-tight pantaloons of the day.

Ms Cormack, a Scottish community worker, says simply: 'I loved the way it looked. I never liked my breasts. I always wanted them to be different in some way. But after I had them done I spent hours looking at them and I feel good about them now.'

Ms Cormack, now pierced in her nose, navel and nipples, feels that her motivations have become more complex as she has become more involved in piercing: 'I was going through a lot of change and self-analysis and piercing became like a rite of passage, a way of asserting my independence. When it's happening it's like a release, a sort of exorcism of bad feelings and emotions from the past.'

But Estela Welldon, a consultant psychotherapist at the Portman Clinic, London, compares body piercing to forms of self-mutilation such as cutting and burning, and believes that it may often indicate psychological distress.

'By enforcing, inflicting or attaching foreign things to the body the person expresses a great deal of conflict with that body. It's about not feeling satisfied or at peace when you have to do something so extreme to make your body acceptable to you.

'It is as if the natural unadorned body simply isn't enough. You'll notice that most of the people who are into this don't just stop at a single piercing. It's extremely compulsive - it's a cycle. You do it, it has this cathartic effect, you feel better for a while, then you start feeling despondent again. It's a holding operation.'

She believes that body piercing may attract more women than men because women are more prone - as with anorexia or bulimia - to turn against themselves.

She makes a distinction between piercing 'socially acceptable' parts of the body such as the ears, and piercing the genitals. 'There is a lot of exhibitionism there, a desire to shock,' Ms Welldon says.

'At first it seems defiant: 'This body is mine, I can do anything I want to it.' But there is a lot of depression there as well. It's as if nothing else belongs to you. How sad to feel that there is nothing else in your life that you can control other than your body.'

Teena Maree, the professional piercer who carried out the public piercing of Ms McCormack, is herself pierced in 23 places, including her eyebrows, tongue and genitalia.

Ms Maree says clients recognise that piercing is more than a 'style thing'. 'People need to assert their individuality and feel special. Over the last year or so, I've seen a lot more people. They come to celebrate anniversaries, mark changes in their lives, even endings.'

Many people associate piercing with gays or sado-masochists, but it is just as popular with suburban married couples, Ms Maree says. 'My clientele is very varied. I get a lot of people from the City and quite a lot in the legal profession.'

She points out that piercing is not illegal. But in a court case earlier this year, five gay men were convicted of assault for consenting sado-masochistic acts. The verdicts implied that any sexual practice which leaves lasting marks could be prosecuted under the law. It means that practitioners of body piercing feel they have to play down any potential sexual thrills, as well as the pain of being pierced.

'If you asked me to tell you what it felt like to have a particularly sensitive part of your body pierced, all I could say is that it is a beautiful experience,' says Ms Maree.

Estela Welldon has her own view. 'You mustn't forget that pain is a source of eroticism to some people. That is why I make the distinction between ear piercing and genital piercing. The difference is the extent of the pain involved.'