The heavily pregnant mother was a passenger in the vehicle when the driver lost control and capsized on a motorway.
As the vehicle turned over she was thrown from the cabin before being crushed by planks of wood that also fell from the truck and tore the tot from her belly.
But shocked paramedics then discovered the crying baby girl lying on a grass verge several metres away.
Incredibly the infant, whose umbilical cord had been severed during the accident, was found in perfect health and without a single scratch.
She is now being treated at the nearby Pariquera-Acu regional hospital’s neonatal intensive care ward.
Police and social services are trying to identify the child’s deceased mother, who was 39 weeks pregnant and was found without any documents.
Elton Fernando Barbosa, the first paramedic on the scene on the BR-116 highway, told Brazil’s A Tribuna newspaper: “It was a serious accident with one reported person deceased.
“When I arrived there, I saw that the truck driver was injured, and he was seen by the first aid team.
He said he found the baby several metres away from the mother, and quickly called for the ambulance to take her to hospital.
He said: “The foetus was literally expelled by the impact on the mother, the impact was so great that this opened up the mother’s belly and the child was ejected.
“She was perfect, healthy, without a scratch. We can say that, in those circumstances, it was really a miracle that she survived.
“I’ll be honest. It was God. By what I saw, I have no idea how she came out alive. The mother was underneath several planks of wood. I don’t know how this child got out of their with her life.”
The paramedic added: “It was emotional. Unfortunaely we had the death of the mother, which is something we always never happens. But in the midst of the tragedy, we were able to save the baby.
“This event has marked my life. I don’t think there has ever been an accident like this in the history of the motorway. We lost a life, but we were responsible for giving life to a girl.”
Solange Batista, a nurse at the Pariquera-Acu hospital, said staff had given the baby, who weighs 6 pounds eight ounces, the name Giovanna, which means ‘protected by God’.
She said: “She is really calm baby, she doesn’t cry, if you play with her she even smiles.”