Hi, I am wondering how long to be concerned about SIDS? at what age does the risk decrease? Thank you

Red Nose accepts the following International definition of Sudden Unexpected Death in Infancy (SUDI - includes SIDS & fatal Sleeping accidents)
“....the sudden unexpected death of an infant less than 1 year of age, with onset of the fatal episode apparently occurring during sleep, that remains unexplained after thorough investigation, including performance of a complete autopsy and review of circumstances of death and clinical history.”
https://rednose.org.au/article/the-triple-risk-model
Therefore SUDI/SIDS does not occur after 1 year of age (according to definition)

Also, 90% SUDI occurs with babies less than 6 months of age.
90% of deaths occurring in the first 6 months of life, with a peak at 2-4 months and few babies dying in the first month.
https://rednose.org.au/article/the-triple-risk-model