One man is charged with impaired driving causing death, following a crash in Wilmot Township just west of Kitchener around 8:30 last night.
Ontario Provincial Police say a 30-year old woman was killed and her three-month old baby critically injured in the collision on Highway 7.
Investigators say the woman died at the scene, and that her baby was airlifted to hospital with life-threatening injuries.
Police say they were passengers in a vehicle that was struck from behind.
Two others in the car suffered minor injuries.