Very young babies are vulnerable to sudden infant death syndrome when placed in car seats and other "sitting devices," warn Quebec researchers.

An analysis of all sudden unexpected deaths among babies up to 12 months of age in the province between 1991 and 2000 suggests premature infants are not at greater risk of sudden and unexplained death from being placed in a car seat, as was previously thought.

But the analysis points to an increased risk in all babies, premature and full-term, in the first month of life when they are sitting up in a car seat or another type of baby seat.

"I think that really, the bottom line of that paper is that let's not concentrate on babies that were born premature," said lead author Dr. Aurore Côté, of the division of respiratory medicine at McGill University Health Centre in Montreal.

"There is a risk, probably, of something happening in a car seat when you're in the first month of life. And I should not say 'car seat.' I should say 'sitting device.' … So the message to parents will be: Don't have a baby less than one month of age spend a long time in a car seat or in a sitting device."

The study was published Thursday in the online edition of the Archives of Disease in Childhood.

The researchers examined coroners' records of the deaths of 508 babies. Seventeen (3.3 per cent) of the deaths occurred in babies who were seated, mostly in car seats. Ten of these were unexplained.

Premature babies were not at greater risk. But those aged under a month, were almost four times as likely to die suddenly while seated as compare to the older babies.

The authors point out that their research indicates that the rate of deaths among seated babies is relatively small at just over three per cent, and that there are no questions about the necessity or safety of car seats.

The chief of the neonatology division of Toronto's Hospital for Sick Children termed the findings interesting and said he thinks Côté and her co-authors may be onto something.

But Dr. Keith Tanswell urged parents not to panic — and not to forgo strapping babies into car seats when they are travelling in vehicle.

Tanswell said infants that aren't secured in a proper car seat are at much greater risk of being injured during a journey than they are of succumbing to SIDS while in a car seat.

"I think you have to take the study as a very interesting study that is suggestive that it may not be ideal to have a baby in a car seat without the head in a neutral position," Tanswell said.

"But the numbers are small and how solid a conclusion and major changes can we suggest on a small study?… I think there are some messages there that these things are worth looking at. But I wouldn't panic at this stage."

Côté also stressed that babies ought to be secured in a car seat while in a moving vehicle, though she advised parents to try not to take infants out for prolonged drives.

She admitted it's not possible to say how long a young baby can safely sit in a car seat or other sitting device. But she advised that if parents have to have a baby in a car seat for longer than 30 minutes they should consider stopping at half-hour intervals to adjust the baby's position to ensure that the head hasn't flopped over, obstructing the infant's airway.

Sudden infant death syndrome is the term applied when seemingly healthy babies under the age of one year die and even an autopsy cannot ascertain a cause of death. Each week, three babies die of SIDS in Canada.

With files from the Canadian Press