Definition of SIDS (sudden infant death syndrome)

SIDS (sudden infant death syndrome): The sudden and unexpected death of a baby with no known illness, typically affecting sleeping infants between the ages of two weeks to six months. Infants with a brother or sister who died of SIDS; babies whose mothers used heroin, methadone, or cocaine during pregnancy; infants born weighing less than 4.4 pounds; children with an abnormal breathing pattern that includes long periods without taking a breath (apnea); and babies who sleep on their stomachs are at increased risk for SIDS.

Since babies who sleep on their stomachs are at least three times more likely to die of SIDS than babies who sleep on their backs, children's health authorities recommend always placing infants on their backs to sleep.