Tiffany Robbins, 26, drove into the path of a truck at the intersection of Victory Drive and Woodstock Road in Acworth, said Lt. Jay Baker, spokesman for the Cherokee County Sheriff's Office.
"Ms. Robbins, who was 7 months pregnant, was conscious and alert at the accident scene," Baker said.
Robbins and her 3-year-old daughter, who was restrained in a car seat in the back of her Honda Accord, were sent to Wellstar Kennestone Hospital.
Doctors performed an emergency Cesarean section on the mother, but the baby did not survive, Baker said.
"After that procedure, Ms. Robbins also died from apparent internal injuries," Baker said.
The driver of the truck wasn't seriously injured.