A baby boy died after being left in a hot car after his mother mistakenly thought she'd taken him inside her house with her other children, an inquest has heard.
Nine-month-old Hugh Lane was left in the car for more than an hour on a summer's day while his exhausted mother assumed he was asleep in his cot in his bedroom.
The temperature in the car was more than 40 degrees on the afternoon of February 4 last year, the Coroners Court heard on Thursday.
State coroner Sara Hinchey ruled Hugh's death the accidental result of a "catastrophic event", and found his mother, Emma Lane, was not criminally responsible.
"There is no one to blame here. It is a tragic accident," Judge Hinchey said.
Hugh was left in the car when Ms Lane took her two eldest children inside on returning to their Mount Martha home at 1.30pm after a busy day of appointments and errands.
It was her habit to take all three children out of the car together, the court heard but the two eldest children were crying when they got home.
When Ms Lane took items from the car and closed the passenger door she believed she had taken Hugh inside, Jodie Burns, the counsel assisting the state coroner, told the inquest.
It was not until before 3.30pm that Ms Lane went into Hugh's bedroom expecting to find him sleeping that she realised the baby was not there, and that she feared he might be in the car.
She screamed for help when she found him in his rear-facing baby seat, Ms Burns said, and she and neighbours rushed him inside the house and cooled him with water, wet towels and a packet of frozen peas.
Ambulance paramedics recorded a body temperature of 37.4 degrees - 37 degrees is normal for children - but despite the efforts to cool the baby, he died in hospital five days later, most likely from heatstroke.
An inquest held earlier this year into the death of a 22-month-old boy left in a car was told people's short-term memories were not infallible, and that the brain did not discriminate between vital information such as remembering to remove a child from the car and something inconsequential, such as posting a letter.
Associate Professor Matthew Mundy, a neuroscientist who reviewed the 2015 death of Noah Zunde, told the state coroner in March that Noah's mother would have had her short-term memory affected by a lack of sleep, her stressed state and changes to her routine when she left him in her car having thought she had dropped him at childcare.
Judge Hinchey said on Thursday the inquest into Noah's death showed the limitations of the human short-term memory.
She said mothers of young children were often sleep deprived and juggling many things.
The court heard Victoria's Department of Education and Training had devised a fact sheet for parents of young children, warning of the dangers of leaving children in cars.
Figures presented at Noah's inquest showed Ambulance Victoria paramedics were called to attend to 1907 children left in cars last year, and 28 of them needed hospital treatment.
Five children died in Victoria in the past decade after being left in cars.