In the acronym SIDS what does the I stand for?

"SIDS" Stand for Sudden Infant Death Syndrome. It is an under studied event where infants die for no apparent reason usually in there sleep in their crib. Sometimes the infant rolls over suffocating in other cases the child just mysteriously dies. Some cases of infanticide are misdiagnosed as SIDS and sometimes actual SIDS cases are found to be murder. In either case a great injustice has occurred.