It happened Thursday along Route 120 in northwest suburban Bull Valley.
Officer Jim Page responded to a call of a baby having a seizure.
He says the 14-month-old boy was blue and appeared to be choking, then he stopped breathing. Page performed CPR.
"I can't remember any other time in my life other than when my children were born where I felt like I needed to cry from being happy but you know the mother, we saved a life.
And we saved a family," said Officer Jim Page, Bull Valley Police Department.
Page says the boy was taken to a hospital but came home on Friday.
He tells ABC7 the child had strep throat.