Babies should be put to sleep on their backs

University of Aberdeen researchers looked at about 13,000 cot deaths which occurred between 1986 and 1998.

Writing in Archives of Disease in Childhood, they said that despite a big fall in cot deaths during the 1990s, numbers were still higher at weekends.

The 'Back to Sleep' campaign in the early 1990s advised babies should sleep on their backs. Deaths fell from 1,700 in 1986 to 395 in 1998.

It is not possible to know for certain why babies are more likely to die at weekends Foundation for the Study of Infant Deaths spokesman

The researchers analysed the number and timing of deaths attributable to sudden infant death syndrome (SIDS), or cot death, from national statistics for England, Wales, Scotland and Northern Ireland.

They looked at deaths between 1986 to 1990, before the 'Back to Sleep' campaign, and between 1993 and 1998, after it.

While there was an overall fall of around 75%, deaths continued to peak on Saturdays and Sundays, continuing to account for just under a third of the total number of deaths.

The researchers found there was actually a small increase after the campaign, with the proportion of deaths at the weekend rising from just over 31% to just over 32%.

The pattern was more evident among babies aged up to four months.

In the second period, almost 4% more babies in this age group died at weekends than babies aged five months or more.

'Can't change lifestyles'

Professor Peter Helms, of the Department of Child Health at the University of Aberdeen, who led the research, told BBC News Online: "It might be that parents 'don't want to bother the doctor', or have problems accessing healthcare at weekends.

It might be that parents 'don't want to bother the doctor', or have problems accessing healthcare at weekends Professor Peter Helms, University of Aberdeen

"Or it could be that people are more relaxed at weekends - maybe they don't have to be up early to get the other kids off to school, or they may lie in after going out on a Saturday night."

He said it would not be possible to change people's lifestyles.

But Professor Helms added: "Healthcare professionals could consider improving access to healthcare at weekends."

A spokesman for the Foundation for the Study of Infant Deaths said: "It has long been known that sudden unexpected infant deaths are more likely to occur at weekends than weekdays.

"There is speculation as to why that may be, but no evidence-based answers.

"Until more is known about why these tragedies occur - through improved investigation of each death and through more basic research into causation - it is not possible to know for certain why babies are more likely to die at weekends."