SIDS is the leading cause of death in infants between one month and one year of age. Most SIDS deaths occur when a baby is between one and four months of age.
Boys are at greater risk for SIDS than girls.
In many SIDS babies, abnormalities are found in the arcuate nucleus , a portion of the brain that controls breathing during sleep and the ability to wake up. A baby with this abnormality may lack a protective brain mechanism that senses abnormal respiration or cardiovascular function and normally leads babies to wake up and take a breath. Babies who sleep on their stomachs get their faces caught in bedding, which causes them to breathe too much carbon dioxide and too little oxygen. Researchers are studying whether this is why sleeping on the stomach is hazardous and why babies with an abnormal arcuate nucleus die when sleeping in this position. A larger number of babies who died from SIDS apparently had respiratory or gastrointestinal infections prior to their deaths.