The mobile is hanging over the crib, the Babygros are folded in a neat little pile and the cupboards are stocked with cotton wool and nappies. The parents-to-be are waiting for the imminent birth of their child. Then the dream topples, and their joy twists into shock, grief and anger. Their 'perfect baby' is disabled, and the nest they have lovingly built seems to mock them.

'You don't realise when you're pregnant, you have this idea of the baby you're going to have and how your life is going to be,' says Joanne Wall, whose son Harry was diagnosed as having Down's syndrome at two days old. 'To have something wrong with your child changes all of that. I felt cheated. I felt like I hadn't had a baby at all: I'd got this other thing, I'd got a Down's syndrome. I felt as if my future, and my baby's future, had been taken away.'

But she had no doubts about wanting to keep him and, with her husband, saw Harry through heart surgery when he was only weeks old. 'He was our son and all we wanted was for him to pull through,' she says. But for many parents the news that their baby has a disability is - for that moment at least - unbearable. Last week a father was given a suspended prison sentence for trying to smother his five-day-old son, diagnosed with Down's syndrome. The family blamed the 'cruel and uncaring' way in which the hospital gave them the information.

Anne Leonard, of the Spastics Society, author of the recent report Right from the Start, says: 'It was amazing how, whatever I talked to parents about, the issue of diagnosis and disclosure eventually came up. Sometimes years later - 20, 30 years later - parents of adult, even middle-aged, disabled sons and daughters had still not completely got over the pain of the way they found out about the disability.'

The very moment of discovery often remains frozen in a parent's mind, like a frame from a recurring nightmare. 'We were in the parents' room in the special care unit,' recalls Ric Adams, whose three- year-old son, Jordan, has cerebral palsy. 'I remember what was on the television - it was Wogan. I can even remember who the guest singer was. Jane had gone out to look at Jordan in his incubator. She came back in tears; she'd just spoken to one of the junior registrars, who said they'd looked at the brain scan and found something which wasn't normal.'

Unlike the birth of an able-bodied baby, the arrival of a disabled child is not seen as a cause for popping the champagne, but as something shameful. One mother of a child with Down's syndrome received a 'get well' card.

'People don't understand what it's like, and they pity you and feel sorry for you,' says Ms Wall. 'People kept asking: 'How's he doing? How's he developing?' Poor child, he was only tiny, he hadn't had a chance to develop at all. But they were very keen on asking how different he was from other children. And I was trying to ignore that and concentrate on how many ways he was the same.'

Children born with disabilities are - and always have been - part of every human society. Yet most parents experience disability as a unique event, as if their child is the very first to suffer.

Carol Dale, whose son was diagnosed as having cerebral palsy at 11 months, remembers: 'We had nobody come knocking on the door, no phone calls. We didn't really know what cerebral palsy meant, so my husband rang my brother-in- law, who had a medical book. He never rang back. He didn't know how to tell us.'

So shameful is the tag attached to a disabled child that many parents initially deny that their child has a disability. 'I hoped that they were going to put their arm around me and say it's not as bad as it sounds. But they didn't. The news just got worse and worse. I kept hoping that they'd made a mistake,' said Jordan's mother, Jane Adams.

The persistent, often insolvable question is: 'Why?' But with many disabilities, there is no known reason. About one in every three cases of cerebral palsy - the most common form of childhood disability - is unattributable. Still, the search for a cause can be consuming. 'For many, many years we wanted to know a cause,' says Brigitte Dell, whose son, Steve, has autistic tendencies. 'I started to have asthma attacks when I was five months pregnant, and to this day my husband thinks that has something to do with it, even though it couldn't possibly affect a child in the womb.'

Antenatal clinics, with the offer of tests for many disabilities from spina bifida to Down's syndrome, can give women a false confidence that every disability is detectable. But as three in every 100 parents find out, this is not the case.

The plethora of advice on diet and exercise in pregnancy can also encourage the mother-to-be to believe it is within her power to ensure nothing will go wrong. So if it does, she may blame herself. Kathleen Pearson's son, Matthew, was born by emergency Caesarean section, and was technically dead for five minutes before being resuscitated for a further 20, a fact revealed to Ms Pearson only 18 months later. 'I was angry at not being told what happened at the birth, but I was also angry at myself because I'd had a general anaesthetic. I felt as if I wasn't there for him. As his mother, you should be able to help your child if anything goes wrong. But because I was under anaesthetic, I couldn't do that.'

Anne Leonard admits: 'At the time of diagnosis, the first shock can give rise to guilt, fear for the future, anger, bitterness - all of these negative emotions. But how quickly and effectively a parent works through them is very much a matter of how supportive the rest of the world is at that time.'

The Spastics Society report points to close links between the attitudes of the medical profession and how the parents feel themselves. Up to 25 medical and related professionals are involved in one child's diagnosis and disclosure, yet only 12 per cent of health authorities have any written guidelines on how they should share the news and offer support.

Although the child in the crib may not be the hoped-for bundle of joy, it is still a bawling, breathing baby. 'I'm a practical person, and I believe that for every problem there's a solution,' says Joanne Wall. 'But with Down's syndrome, there's no solution. You can't cure it, it's just going to be there, always, and it's more a matter of acceptance. You have to come to terms with a different kind of future, a different kind of life. But just because it's different, that doesn't mean it's going to be worse.'

'Right from the Start: Looking at Diagnosis and Disclosure', from the Spastics Society, 12 Park Crescent, London W1N 4EQ, pounds 4.95.

Cerebral Palsy Helpline: 0800 626216.

(Photograph omitted)