Nobody knows what causes cot deaths. That is a fact. You put your baby down to sleep and for some unknown reason its breathing reflex stops. Nobody knows what causes many miscarriages either: sometimes they just happen.

However, if you read the newspapers last Wednesday, you might think differently. 'Ashes to ashes', screamed Today. 'A baby dies of cot death every day because its mother smokes.' In the Daily Telegraph 'Smoking kills 5,000 babies a year'. The Independent ran the headline 'Smoking by mothers 'kills 4,000 foetuses' ' and went on to say that the Royal College of Physicians believes more than 4,000 healthy foetuses are miscarried each year because of maternal smoking.

I had a miscarriage with my first pregnancy. I was shopping and suddenly I was doubled up with cramps and bleeding heavily. After the dead foetus was removed, all I wanted to know from the doctors was, why? Why me, with my healthy, totally Eighties, non-smoking, good eating habits? I needed some facts but I never got them. The obstetrician didn't know why it had happened. 'Don't think about it,' she said. 'You can try again.'

But every woman who has ever lost a baby without knowing why does think about it. 'These reports make me feel hysterical,' says Debbie, a normally calm mother of three who lost a baby in a cot death last year.

'Every few weeks it's something different. One minute they say every baby must have a new mattress, then they change their minds. Now this. I still feel I don't know how I could prevent it happening again, and though I know I did all I could for my baby, I feel guilty.'

Sue Howe, head of the Cot Death Society, wishes she could protect her members from press reports like last week's. 'Those headlines don't help anybody who's had a cot death, or help us to support them,' she says. 'What about all those women who've never smoked - what are they supposed to believe? Every month there's a new horror headline regarding cot death and meanwhile we're still losing our babies.'

Ashley Woodcock, consultant physician at Wythenshawe Hospital, Greater Manchester, was on the working party that issued the Royal College of Physicians report. He stands by the figures and explained some of the motivation behind the report. 'There was a great deal of publicity about positioning babies in bed a few months ago,' he says.

'We felt that the evidence on smoking had got lost and that it was very important to remind mothers of the negative effects of smoking. We tried to give a numerical size to it so people can understand the danger. But if we said there's 27 per cent excess mortality in smokers, who would pay attention?'

But Sue Howe points out that the information that came out last week was not new. The facts are that people who smoke are likely to have smaller babies or premature babies, and both these categories are more at risk of dying unexpectedly in a cot death. This has been known for years. 'But the way this report has been presented it appears to be saying, 'If you smoked and your baby died, you caused it,' ' she says.

'Nobody fully knows what causes cot deaths. Not long ago we were told cot death victims must all have been murdered by their parents.'

As mothers, the main substance we inhale is first-cut, top- quality guilt. It is especially acute for those who have lost babies in unexplained circumstances. Panic-inducing headlines simply add to our guilt, without helping.

The mothers I spoke to last week all said they had had enough. As one put it: 'I'm like every other mother; my first reaction is, 'Oh no, what am I doing wrong', but three months later there's a new theory. I ignore them now. Panic doesn't help me to mother my kids.'