The baby, his mother, 24, and the 31-year-old driver were travelling along River Road near Collie when the car left the road and hit a tree on Saturday night.
The baby’s grandfather has said he believed his daughter unclipped her son’s seat buckle before the crash because he was choking.
Fernley Maidment said his daughter had paid top dollar for the car seat for his grandson, and he believed it would have been a different scenario if he had not been choking.
Police said they were investigating the circumstances of the crash.
The car after the crash that claimed the life of a baby boy. Image via ABC.