Using a fan or opening a window could reduce the risk of sudden infant death syndrome by improving ventilation, researchers suggest.

Since 1999, the incidence of SIDS in the United States has decreased by more than half to about 2,100 in 2003, the researchers said, as more parents followed the "Back to Sleep" campaign and placed infants on their back to sleep.

But SIDS remains a leading cause of death in infants, leading the team to look for other ways to reduce the risk.

SIDS, also known as crib death, refers to the sudden and unexpected death of an apparently healthy infant under one year of age.

In the October issue of the Archives of Pediatrics & Adolescent Medicine, researchers in California found that the risk of SIDS for infants in rooms with a fan was 72 per cent lower than those who slept in rooms without a fan.

Opening a window also reduced the risk by 36 per cent, the researchers said.

"The baby's sleeping environment really matters," said the study's senior author, Dr. De-Kun Li of the Kaiser Permanente Division of Research in Oakland, Calif. "This seems to suggest that by improving room ventilation we can further reduce risk."

Preventing build up of carbon dioxide

The researchers interviewed mothers of 185 infants who died from SIDS and another 312 infants of similar race and age. All mothers were questioned about their baby's sleep habits.

It's thought that affected babies may have brain abnormalities that prevent them from gasping and waking up when they fail to get enough oxygen.

The ventilation may help by preventing carbon dioxide from building up around a baby's nose and mouth so they are less likely to breathe in exhaled air, the researchers speculated.

Among babies who died of SIDS, three per cent had a fan in the room during their last sleep, compared with 12 per cent in the other group. Using a fan also seemed to reduce the risk more in warmer rooms, the researchers said.

The National Institute of Child Health and Human Development, which helped pay for the study, said the ventilation findings need to be confirmed by additional research before it could recommend running a fan to prevent SIDS.

Placing infants to sleep on their back remains the best way to reduce the risk, the group said.

Other established recommendations include:

• Using a firm mattress.
• Avoiding soft bedding.
• Preventing overheating.
• Not smoking during pregnancy or around babies.

Each week, three babies die of SIDS in Canada, according to the Public Health Agency of Canada.

With files from the Associated Press, Reuters