SIDS is sometimes called crib death because the death occurs when a baby is sleeping in a crib. It is the major cause of death in babies from 1 month to 1 year of age.
Death occurs quickly, usually during a sleep time.
Some SIDS babies are born with brain abnormalities that make them vulnerable to sudden death during infancy. Babies born with defects in other portions of the brain or body may also be more prone to a sudden death. These abnormalities may result from exposure of the fetus to a toxic substance, or a decrease in oxygen. Cigarette smoking during pregnancy, for example, can reduce the amount of oxygen the fetus receives. Normally, babies sense when they do not get enough air and the brain triggers the babies to wake from sleep and cry.