Nine out of ten cot death victims had mothers who smoked during pregnancy, a major study has revealed.
The scientists who carried out the research warn that mothers to be who smoke are four times more likely to see their child die from cot death than non-smokers.
The report, from Bristol University's institute of child life and health, calls on the Government to ban expectant women from buying tobacco.
Its authors say smoking in the presence of pregnant women and infants should be seen as being 'anti-social, potentially dangerous and unacceptable'. Ministers are considering whether to rewrite their advice for mothers-to-be on smoking.
Authors Peter Fleming and Dr Peter Blair based their analysis on the evidence from 21 international studies on smoking and sudden infant death syndrome.
Dr Blair said: 'If smoking is a cause of SIDS, as the evidence suggests it is, we think that if all parents stopped smoking tomorrow more than 60 per cent of SIDS deaths would be prevented.'
Around 300 babies a year die of cot death in Britain, usually between the ages of one and four months.
The report, to be published later this week, calls on the Government 'to emphasise the adverse effects of tobacco smoke exposure to infants and among pregnant women'.
It found that many women are still ignoring the risks of smoking when they were carrying a child.