Inquiries are continuing into the death and the investigation was expected to take some time.
The woman was believed to have accidentally left him in her car last Friday morning under the mistaken belief she had dropped him off at daycare.
It was not until that afternoon that she realised the toddler was in the car, which had been parked in the hospital carpark in the 26C summer heat.
A witness had described how the woman collapsed and had to be pushed through the hospital in a wheelchair, "clutching her chest and screaming", after the discovery.
Whanganui District Health Board has offered help to members of the public who witnessed the incident, saying anyone who felt like they needed support was welcome to get in touch.
Yesterday, several sources said the boy's father was overseas when the tragedy happened.
- NZME.
