Sally Clark, jailed for life for murdering her wto baby sons, walked free this week following an appeal. Women's Editor Christen Pears talks to a North-East mother whose son died of cot death and reports on how difficult it is to diagnose.

TWENTY-two years after her five-week-old son Simon died, Barbara Hetherington still has no idea how or why. She had taken him out for a walk just after his morning feed and when they returned, he was asleep.

"I didn't want to wake him up so I left him in the pram to sleep. He didn't wake up for his next feed. I went through and he was dead in the pram," she recalls. "Unless you've been through it, you can't even begin to imagine what it's like. It was a nightmare and you live with it for the rest of your life. Everyone kept telling me I wasn't to blame but you can't help feeling guilty. You wonder whether you should have done something different."

Simon was Barbara and her husband Michael's second child and the couple, who live in Staindrop, in County Durham, went on to have two more after his death.

"Simon was on my mind all the time. I was terrified it was going to happen to them as well because it's something you have absolutely no control over. It can happen to anyone, at any time and there's very little you can do about it."

Every day, somewhere in Britain, a healthy baby dies suddenly and unexpectedly. The cause is registered as cot death, or Sudden Infant Death Syndrome, but no-one knows how or why they died. The syndrome usually affects children under one year old, with 88 per cent of them less than six months. It affects more babies from low income families and 60 per cent of victims are boys.

Cot death has been described as a "diagnosis of exclusion". If a post-mortem examination fails to establish the cause of the baby's death, it is classed as cot death. Because it is so difficult to diagnose, it can lead to confusion, especially when there are suspicious circumstances.

Yesterday, Maxine Robinson appeared at Peterlee Magistrates' Court, accused of murdering her five-month-old daughter at her home in Pelton in 1989. A post-mortem examination put the death down to cot death but the case was re-opened by Durham Police.

On Thursday, solicitor Sally Clark was freed from life imprisonment for the murders of her two baby sons. The 38-year-old from Cheshire was jailed in 1999 after being accused of smothering her 11-week-old-son Christopher in December 1996 and shaking eight-week-old Harry to death in January 1998.

During the appeal hearing in London, the judges were told that crucial medical evidence relating to Harry, which could have cleared Mrs Clark, had not been disclosed to the defence team during the original trial. Paediatrician Professor Roy Meadow, appearing for the prosecution, had also told the court the likelihood of two cot deaths in one family was one in 73 million, but recent research suggests the real figure could be as low as 100 to one.

Barbara says: "Saying something like that is just pure ignorance and that sort of ignorance is dangerous. People look at you with suspicion when your baby dies of cot death anyway but when so-called experts, pathologists and the police don't understand what they're dealing with, things like this can happen quite easily.

"After Simon died, I did a lot of campaigning, trying to raise awareness about cot death, not just with parents but with the police as well. Unfortunately, what happens after your baby dies is still so random and that has to change."

Barbara believes more needs to be done to educate people about the dangers of cot death, which she believes is still a taboo subject.

"Although we don't know what causes cot death, there are things you can do to help prevent it - not putting your baby on its front to sleep, for example - but a lot of people don't get enough information. They need to know these things before their baby is born."

Cot death hit the headlines in 1991 when TV presenter Anne Diamond's son, Sebastian, died aged just four months. It raised the profile of the syndrome and a subsequent campaign, introduced by the Foundation for the Study of Infant Deaths (FSIDS), cut cot deaths in Britain by half.

Although the number of fatalities has decreased, almost 400 babies die each year.

Since it was founded in 1971, the FSIDS has provided more than £8m for research but other, independent studies are being carried out all the time. Last year, researchers at Sleep Lab on the University of Durham's Stockton campus, completed a study into cot death using twins.

Barbara says: "I don't think we will ever know the exact causes of cot death but research is helping us to understand more. It's a terrible thing to have to go through something that colours your life forever, and we have to do all we can to help people prevent it."

* You can contact the FSIDS helpline on 0870 7870554.

HOW CAN YOU REDUCE THE RISK OF COT DEATH?

Place your baby on their back to sleep.

Cut smoking in pregnancy - fathers too.

Do not let anyone smoke in the same room as your baby.

Do not let your baby get too hot.

Keep your baby's head uncovered - place your baby with their feet to the foot of the cot, to prevent wriggling down under the covers.

If your baby is unwell, seek medical advice immediately.

Parents shouldn't share a bed with their baby if they are smokers, have been drinking alcohol, take drugs or medication that makes them drowsy or are excessively tired.

Keep the cot in your bedroom for the first six months.

Avoid falling asleep on the sofa with your baby.