Paramedics were called to the Cumberland Street home about 3.45am on Wednesday where they found the toddler in a serious condition. He died in hospital soon after.

Preliminary autopsy results showed pneumonia and cardiomyopathy were among a range of factors that ­contributed to the boy’s death.

Police are also investigating the circumstances ­surrounding the boy’s death.

The autopsy did not show a conclusive cause of death and further testing will be carried out.

Central Hunter crime manager Detective Inspector John Zdrilic said police would wait for the full autopsy results to decide if there were any suspicious circumstances.

“Anytime that a 19-month-old dies it’s tragic and for the sake of everybody we are looking at the circumstances,” Inspector Zdrilic said.