Sudden infant death syndrome (SIDS) is the unexplained death of infants under 1 year of age. Researchers have identified factors that may increase the risk of SIDS, such as sleeping on the stomach or side, soft sleeping surfaces, overheating, and secondhand smoke exposure. The most effective prevention strategy is to always place babies on their backs to sleep. Nurses educate parents on risk factors and recommend prevention measures like back sleeping, a safe sleep environment, breastfeeding, and immunizations.