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Potential SIDS cause found

22 Oct 2010

A baffling condition Sudden Infant Death Syndrome (SIDS) that leads to the unexplained deaths of many infants worldwide may have been explained in new Australian research. The researchers monitored babies as they slept on their bellies and found that they have reduced blood pressure and an increased heart rate, compared with when they slept on their backs as recommended. This effect is seen more in babies aged two to three months, the age when babies are most at risk of SIDS.

Associate Professor Rosemary Horne from the Ritchie Centre at Melbourne's Monash University said, "For the last 15 years now we have been looking at what is different about babies sleeping on their tummies." It is only now that a concrete reason is within reach she added.

Dr. Horne and her team developed a non-invasive method for tracking the blood pressure of babies just weeks old, using a monitoring device normally used on an adult's finger. They monitored nearly 40 healthy, full-term babies sleeping on their tummies and backs. Those on their stomachs had about a 5% reduction in blood pressure, which could result in less oxygen reaching a baby's brain. The drop-off in blood pressure was "not a large amount", Dr Horne said. However she warned that the changes could be significant in pre term babies. She also said that another reason why sleeping on tummies can become serious is that these babies found it harder to rouse themselves from sleep should they have a problem. A baby on its tummy with its head turned to one side could constrict arteries leading to the brain.

"If you put these in combination, you've got lower blood pressure, impaired arousal and now, we think, reduced oxygenation in the brain...If there was a baby perhaps more vulnerable to SIDS, a baby born pre-term or a baby whose mum smoked during pregnancy, it may be even more important," she explained.

The problem...

Dr Horne said, "The incidence of SIDS has reduced 50 - 80% worldwide and has been very successful in Australia...I think most new mums would all know this, but in some other countries, particularly the US, up to 30% of mums still put their babies to sleep on their tummies...The reason they sleep better is because they don't wake up as well, and that's the problem."

The research was presented at the 22nd Annual Scientific Meeting of the Australasian Sleep Association and the Australasian Sleep Technologists Association, in Christchurch, New Zealand.