A three-year-old boy who was crushed by a car seat had trauma injuries similar to those of a victim in a car crash, a court has heard.
Alfie Lamb died after his mother's boyfriend allegedly reversed his seat into him during a car journey in 2018.
A paediatric pathologist told the Old Bailey the toddler's death was "unnatural" and appeared to have been caused by an "increase in pressure."
Adrian Hoare, 23, and Stephen Waterson, 25, both deny manslaughter.
Alfie was found unresponsive as the pair arrived at their home in Croydon following a shopping trip to Sutton with two others on 1 February.
The court has heard the toddler had been in the back footwell during the journey and cried out "mummy" when Mr Waterson pushed back his seat.
Dr Andreas Marnerides, who carried out a joint post mortem examination on Alfie's body, told the jury the three-year-old had been "healthy" and there was no "natural explanation" for his death.
"We had positive findings it was unnatural, it was trauma related," he said.
Dr Marnerides said the toddler's injuries were similar to those seen in road traffic collisions and there was "positive evidence" they were caused by an "increase in pressure in the body."
Lots of external petechial haemorrhages - tiny red spots caused by ruptured veins - were found on Alfie's head and body as well as inside his chest cavity, the court heard.
Dr Marnerides said evidence of internal bleeding was explained by impact to the right side of the body.
Jurors were also told Alfie's cause of death was given as ischemic brain injury caused by deprivation of blood or oxygen and compression asphyxia.
Ms Hoare denies manslaughter, child cruelty and common assault on Emilie Williams, who was also in the car
Mr Waterson denies manslaughter and the intimidation of the car's driver Marcus Lamb.
The couple and 19-year-old Ms Williams have pleaded guilty to conspiring to pervert the course of justice by making false statements to police.
The trial continues.