Sue Lester, 45, is a proud mother of three children. In every room of her neat house on the outskirts of Bristol are photographs of her children. There's her eldest, 24-year-old Leanne, a nurse; her youngest, 18-year-old Jacob, on a university gap year; and her middle child, 19-year-old Nathan. They look like one happy family - except they aren't. Nathan does not live in the home; he has only occasional contact with his siblings and was put up for adoption by Sue and her former husband when he was six months.

The other difference between Nathan and his siblings is that he was born with Down's syndrome, a condition Sue knew very little about when she was pregnant in 1989. “I'd never come across it before, I didn't know anyone with Down's, nor did my friends or family. When the doctor told me about Nathan he said, ‘It's not life-threatening, he's not going to die, he's a Mongol, he has Down's syndrome'. And he gave me three leaflets.”

Sue was 25, as she puts it “no more than a kid”. She was traumatised by the diagnosis. “It was like a nuclear bomb going off in the middle of this quiet little life.” She thought, why me? What have I done? How can I take him home and show my friends? “It sounds awful now but I remember thinking that it would be easier if he died and then I would not have to explain to everyone what had happened.”

Sue admits that, because of her age, her ignorance of disability and the stigma that surrounded conditions such as Down's, she “couldn't cope” and put Nathan up for adoption. It's a decision that she has struggled with ever since. If she had a Down's baby now, Sue is adamant that she would keep the child because she's older, feels better able to deal with the challenges and, because everyone is so much better-informed now that it is no longer regarded as an “embarrassment”.

This week, a survey of Down's Syndrome Association members found that more parents are choosing to go ahead with Down's syndrome births because of religious beliefs, strong opposition to abortion, better life chances for the children and, significantly, a big shift in society's attitude. Put simply: people are much more accepting of Down's syndrome than they were when Nathan was born.

It's welcome news to parents such as Sue, for whom the pain of adoption is still raw. Not long after Nathan was adopted, Sue's marriage broke down and she suffered from severe depression. She was put under psychiatric care: “I was getting panic attacks and was crippled by anxiety. I wouldn't go out and didn't want people to see me. I felt as if everybody was talking about me, everybody knew and they were all pointing fingers - it was a very sad time in my life.”

Almost twenty years on and Sue credits much of the “easing of her guilt” to the mother who adopted her child - Alex Bell, a remarkable woman who has adopted and fostered seven children with Down's. It was Alex who encouraged Sue to enter into an “open adoption”, whereby the birth parent maintains regular contact with her child. Sue phones Nathan every week, sees him regularly and spent a week with him at Disney World, Florida for his 18th birthday.

But while reports about society's increasing acceptance are encouraging, professor Joan Morris, director of the National Down Syndrome Cytogenetic Register, sounds a note of caution. Morris points out that 92 per cent of women who have an antenatal diagnosis of Down's syndrome decide to terminate the preganancy. This proportion has not changed since 1989, when screening was introduced.

“The number of Down's syndrome pregnancies has significantly increased, mainly because of a shift in maternal age - a much larger proportion of women are having babies later in life when the risk is much higher,” says Morris.

Patricia Johnson, 54, from north Lincolnshire, was one mother who chose not to be screened when she was pregnant with her third child. Patricia says that as she doesn't believe in abortion, any test would have been irrelevant. However Patricia, like Sue, was also unprepared for the shock of being told her much-longed for baby, Thomas, born in 1983, had Down's. “You mourn for the child that's not there and you think of all the problems ahead and how you are going to cope,” she says.

Patricia coped better than most - she was a nurse for children with special needs. “I knew what was going to be on offer, I knew it was going to be hard but I knew I was going to make him the bravest or the brightest or the cleverest Down's - and I was quite determined.”

Patricia fought for every resource available. It was hard, for not only was there not much help, but she had Tom's two brothers to look after and a husband who worked in the oil industry and who was away for weeks at a time. Patricia was not prepared for the fact that he was also autistic - a diagnosis that didn't come until he was much older. “He'd go to bed at 1am and then be up again at 4.30am. He'd want to watch TV or play with toys, sometimes he'd have tantrums.” Patricia was exhausted: “You feel isolated and you just want it to go away, but it won't, you've got a physical being. It is difficult, but I love him to pieces and he's a beautiful child, but I did used to think, somewhere in there is my little boy.” After much battling with social services, Patricia arranged long-term foster care for Thomas when he was 15. Again, with Alex Bell, the single mother who adopted Sue's son Nathan. Patricia says she feared for Tom's future - for when the time came that she could not cope and her son would be taken into care. “I didn't want social services to make decisions based on finance and convenience. I wanted to make those choices for Tom while I was young enough to fight.”

Thomas's is, like Nathan's, an open adoption. Patricia can phone him and sees him regularly and for when he stays, his bedroom is the same as it always was. It's an arrangement that has worked well.

Patricia says if she had a Down's syndrome baby now things would be easier - and she says that it's unlikely that people, especially the “older generation”, would be so rude about a child with disability. “If I took Tom to the supermarket you would often hear people say he should be kept at home.”

But she feels that, although there is a change for the better, there is still a long way to go when it comes to long-term care. “There's always that question at the end of the day - what happens when you are not there? As a parent at 70 or 80, it would have broken my heart if Tom had gone into a placement where he might not be happy. I want the best for Thomas but it is very hard, I miss him so much. I never, ever, will come to terms with the guilt of giving Thomas away of letting him go to live with someone else.”

A Mother Like Alex will be broadcast on Sky Real Lives, Channel 243, on December 3 at 9pm. A Mother Like Alex by Bernard Clark is published by HarperTrue, price £6.99

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