News-Medical -- 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 rates, 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.