Sudden Infant Death Syndrome (SIDS) is the unexpected and unexplained death of an apparently healthy infant, usually between 2 to 6 months of age. While the cause is unknown, risk factors include being male, premature or low birthweight, or exposure to tobacco smoke. Preventing SIDS can be done by reducing risks like placing infants on their backs to sleep in an approved crib with no soft objects, avoiding overheating, and not smoking around infants.