A 36-year-old mother told a doctor that the death of her 14-month-old son from what prosecutors call a "lethal cocktail" of prescription drugs was unintentional, a court heard this week.

Emma Barnett is accused of murdering her son Oakley and told a paediatrician "I didn't mean to" following the child's death, according to testimony presented to jurors.

Prosecutors allege Barnett killed the toddler to prevent him from being taken into care by authorities. The specific circumstances leading to the child welfare concerns were not detailed in court proceedings.

The case centers on the administration of prescription medications that allegedly caused the child's death. Medical testimony is expected to detail the specific drugs involved and their effects.

Barnett's statement to medical personnel following her son's death forms a key part of the prosecution's case as they seek to establish her intent and state of mind at the time of the alleged crime.

The trial is ongoing, with additional testimony expected from medical experts and investigators involved in the case.