Despite a widespread national campaign on the dangers of babies sleeping on their stomachs, more than half of the victims of Sudden Infant Death Syndrome (SIDS) were placed in the wrong position by their parents or caregivers, according to a new Canadian study.

The study, published in the latest issue of the journal Pediatrics, studied the sleeping position in 157 SIDS cases between 1991 and 1997 in Montreal.

"This shows us that even though the national campaigns have had a big effect on reducing SIDS incidences, still the babies that are dying of SIDS are found prone [on their stomach]. And in many of those cases, they are being changed to a prone position by a parent or caretaker," said Dr. Robert Brouillette, professor of pediatrics at McGill University.

The study found that 88% of the SIDS victims were found on their stomachs, even though many of them did not start out sleeping in that position. In questionnaires completed after the infant's death, parents said they changed the sleeping position because of "crying, irritability or poor sleep," while secondary caregivers said they had always placed other infants on their stomach, and believed infants sleep better in that position.

Dr. Brouillette, who co-wrote the study with his colleague Dr. Aurora Coté, said parents and others do not always heed the advice of doctors, particularly when they have had other children.

"You'll find that a parent where it's not the first baby will say, 'My other baby slept prone and didn't die of SIDS," he said.

Experts cannot determine conclusively that sleeping on the stomach causes SIDS, but international campaigns that have pushed the non-prone sleep position for infants have dramatically reduced the numbers of infant deaths.

In Montreal, the number of SIDS cases has been cut in half since national education campaigns were launched in 1994, dropping from about 70 deaths a year in 1992 to about 30 deaths a year in 1997.

"The national change in sleep position for babies has been, by and large, quite complete, but this shows us that there are pockets where the message is not getting through," said Dr. Brouillette. "I'm not sure if we know where all those pockets are in Canada."

The study found there were no significant differences in the age, education or geographic location of the parents of babies who were placed on their stomach during sleep.

Similar studies in the United States have found higher incidences of prone-sleeping SIDS cases in lower-income families.

In the Canadian study, the average age of death was 13.7 weeks.

Of the 139 babies found dead in the prone position, 93 normally slept that way and 64 slept in other positions.

Dr. Brouillette said part of the explanation is that some babies learn to switch themselves to the prone position. But another large part of the problem is not getting the message out to certain groups, such as daycare centres, babysitters and grandparents.

He said the findings of the study, which were completed under the auspices of McGill's Jeremy Rill Centre, named after a baby who died of SIDS, demonstrate the need for continued public education campaigns.